Planed Finish VS Sandpaper - Microscopic View

[Normand Leblanc]

Found this video.

https://www.youtube.com/watch?v=6ngakY8jbtY

Normand

[Joe Tilson]

Thank you Normand. This just answered my question on the thin shaving, think again thread.
Have a blessed day.
Joe

[Prashun Patel]

I can plane some things with ease, others with supreme frustration. I'm in awe of those who can plane everything with ease. I approach each project with the intention of using no sandpaper, and then inevitably hit some vicious tear out and have to resort to it.

[Luke Dupont]

I can plane some things with ease, others with supreme frustration. I'm in awe of those who can plane everything with ease. I approach each project with the intention of using no sandpaper, and then inevitably hit some vicious tear out and have to resort to it.

Same here!

I'd like those proponents of using planed finishes exclusively to go more in-depth on how they actually manage to plane anything, and leave a good surface!

I don't doubt that it can be done! I'm just curious how.

[Andrew Hughes]

Same here!

I'd like those proponents of using planed finishes exclusively to go more in-depth on how they actually manage to plane anything, and leave a good surface!

I don't doubt that it can be done! I'm just curious how.

Picking wood that can be planed.And choosing the boards that have the grain running out on the edges helps.
Stay away from large oval cathedral grain,Knots,and highly figured woods.
Sometimes I can plane most of a build using this strategy.
Knots are the worst I like the way they look in alder.But they are a pain in the a**

Cool video
Aj

[Brian Holcombe]

Same here!

I'd like those proponents of using planed finishes exclusively to go more in-depth on how they actually manage to plane anything, and leave a good surface!

I don't doubt that it can be done! I'm just curious how.

The short answer is that is a combination of reading the grain direction and using the chip breaker effectively. Once you form a set of diagnostic tools (reading the shaving) you can fix pretty much anything that troubles you.

[Frederick Skelly]

OK. I'll admit it - I don't have a CLUE what the conclusion was on that video. Can someone who did please spell it out for me? And how did you conclude this without subtitles in english? (So I can go back, watch it again, and get it this time.)

Thanks guys.
Fred

[Warren Mickley]

I have planed all boards since 1976. I last sanded in 1978. Finishing a board that is not sanded is different and it takes experience, but is not difficult. Sometimes you have to avoid reading the can or an article because the expert many never have seen a fine surface or know how to take advantage of it.

It might be more helpful to think of planing as an art rather than a science. If you are thinking there is some trick or some 1-2-3 recipe, you might be a bit on the wrong track. For this type of thinking it is helpful if you have been trained in some other art. Although it is helpful to watch someone else or have them watch you, to try their plane and have them try yours, good results come from practice and discernment.

[Patrick Chase]

I have planed all boards since 1976. I last sanded in 1978. Finishing a board that is not sanded is different and it takes experience, but is not difficult. Sometimes you have to avoid reading the can or an article because the expert many never have seen a fine surface or know how to take advantage of it.

It might be more helpful to think of planing as an art rather than a science. If you are thinking there is some trick or some 1-2-3 recipe, you might be a bit on the wrong track. For this type of thinking it is helpful if you have been trained in some other art. Although it is helpful to watch someone else or have them watch you, to try their plane and have them try yours, good results come from practice and discernment.

Out of curiosity, what sorts of stains and first finish layers (sealer if any or first layer of topcoat otherwise) do you typically use?

[Patrick Chase]

OK. I'll admit it - I don't have a CLUE what the conclusion was on that video. Can someone who did please spell it out for me? And how did you conclude this without subtitles in english? (So I can go back, watch it again, and get it this time.)

Thanks guys.
Fred

Normand was highlighting the fact that a water drop meniscus has a much higher angle (indicating higher surface tension and lower wettability) on the planed surface than on the sanded one. Joe's point was that certain finishes might not wet out across the surface as a consequence, and he's right. So is Warren, though - the sorts of finishes that you'd actually want on a finely planed surface mostly work with some practice.

[Normand Leblanc]

If there is a part of woodworking where I struggle it's the finishing. I'd be very interested to know what Warren (or others) use and how they do it.

Normand

[Frederick Skelly]

Normand was highlighting the fact that a water drop meniscus has a much higher angle (indicating higher surface tension and lower wettability) on the planed surface than on the sanded one. Joe's point was that certain finishes might not wet out across the surface as a consequence, and he's right. So is Warren, though - the sorts of finishes that you'd actually want on a finely planed surface mostly work with some practice.

Thank you Patrick. So the conclusion is that, the planed surface is so smooth (wrong word, I know) that water beads up on it? Whereas the water doesnt bead as much on the sanded surface - thereby indicating it isnt as "smooth"?

[Normand Leblanc]

So the conclusion is that, the planed surface is so smooth (wrong word, I know) that water beads up on it? Whereas the water doesnt bead as much on the sanded surface - thereby indicating it isnt as "smooth"?

I think that a planed surface is like burnished and that could explain why there is a large surface tension (barrier) when comparing with a sanded surface where the material has been torn from the surface.

On this website, which is about "Surface treatment of wood",
https://www.kruss.de/applications/surface-treatment-of-wood/
they say:"The difference between the contact angle measured during wetting (advancing angle) and de-wetting (receding angle) is referred to as hysteresis. This quantity describes the effect of roughness on wetting, which is very important in the case of wood."
The contact angle seems to be the angle between droplets and the surface. In the video, the contact angle for a planed surface was obviously very high.

Normand

[Patrick Chase]

Thank you Patrick. So the conclusion is that, the planed surface is so smooth (wrong word, I know) that water beads up on it? Whereas the water doesnt bead as much on the sanded surface - thereby indicating it isnt as "smooth"?

Smooth is a reasonable word choice here. Water has very poor wettability on smooth surfaces, much worse than most real-world finishes. Sanded surfaces have "hairs" that wick the water across the surface and thereby improve wetting.

As far as I can tell the video Normand linked was using the water drop to demonstrate how smooth the planed surface is, not to make any sort of comment about finishing.

[Patrick Chase]

I think that a planed surface is like burnished and that could explain why there is a large surface tension (barrier) when comparing with a sanded surface where the material has been torn from the surface.

Planed surfaces don't have crushed structure as you would see from burnishing. In fact they have much more "open" structure (esp pores) than sanded surfaces.

I think that the meniscus angle on the planed surface represents the "true" surface tension of water on wood. The angle on the sanded surface is greatly reduced by the presence of torn fibers (a.k.a. "hairs") on top of the surface, which spread the water droplet out via capillary forces.

When I did a lot of ski racing this was a big issue when sanding base repairs etc. If you didn't get rid of all of the "hairs" then they would increase wettability and therefore drag. You want any liquid water in the ski/snow interface to bead instead of "sheeting" (this is exactly why we wax skis), so anything that increases wetting is bad news. Hairs from sanding are extremely bad news. I've seen pictures of water droplets on "hairy" vs "de-haired" ski bases that look exactly like the ones you got from the video :-).

[Derek Cohen]

The wood I work is considered challenging, however it has become an everyday event to plane it, and after doing so for 20 years, it is straight forward. Occasionally I use high angled planes still, but mostly I use a chipbreaker to control tearout. Doing so is the easy part of planing.

I still consider the harder part lies with profiling and setting the blade. In this regard it is achieving a desired degree of camber, and the ideal depth of cut, so that the final surface is both flat and that this is achieved efficiently.

I am about to start on a kitchen revamp. This will entail replacing all the cabinet doors and drawer fronts with Rock Maple Shaker frame-and-panel styled doors. There are about 25 doors in all and about 10 drawers. The wood will be finished in a poly varnish, or similar, because this is waterproof.

One of the design issues lies with the panels: they need to be dead flat and not show plane marks. By plane marks I am not referring to tracks, but to the very fine scallops that are created by a cambered blade. These will show up when light rakes across the surfaces. Ordinarily I like this, but it is not a desired feature for this kitchen. Consequently, my plan is to sand the panels. I rarely use a sander, and cannot recall when I last did so, since I would rather scrape than sand with furniture. However I do have a Festo ROS (the name of which is a give away ... what Festool became about 20 years ago), and Abranet sanding disks are magic. The panels will be planed and then finish sanded to 400 grit.

This is not a case of "which is better, planing or sanding?", but one of horses for courses. Reluctantly.

Any thoughts?

Regards from Perth

Derek

[Warren Mickley]

I tend to use stuff like water stains, shellac, oil, and wax. If the surface is fine, you can get away with thin coats.

[Derek Cohen]

Warren, those are the finishes I use as well with furniture. I'd use them in the kitchen if they were waterproof and resistant to heat, steam, etc. I'd rather use a finish I can rub on. I have little experience with spraying, and am happy to keep it that way. Any comments on the durability of the above finishes in a kitchen?

Regards from Perth

Derek

[Stewie Simpson]

If your after a burnished finish similar to what's seen within that video, the hand plane your using for your final pass needs to have a wooden sole. A metal sole wont do it, regardless of how fine you set your shaving. Old school knowledge that wasn't restricted to Japan.

Stewie;

[Stanley Covington]

The video is focused on the skill of the miyadaiku carpenter, and the difference between a planed surface and a sanded surface. It does not touch on finishes. The conclusion the video makes is one sentence: "Sandpaper crushes the wood's cells, whereas planing leaves then cells cleanly cut and whole, rejecting water absorption." So, while the images in the video are instructive, the words are not all that helpful.

We discussed this subject at some length in another thread a couple of weeks ago.

Water beads due to "hydrogen bonding," a phenomenon that causes hydrogen atoms to want to clump together. This phenomenon is absolutely essential to the ability of a tree to suck water from the tips of its roots, through the zylem tissue conduits, and out its leave's surface. Note that water is not forced up the tree, but rather sucked up by negative pressure induced by evaporation of water at the leaves. This works only because of hydrogen bonding, the same force that makes water bead up. It won't happen with alcohol, or lacquer thinner, or any other liquid besides perhaps mercury.

The traditional finish for many woods in Japan, in both exterior and interior environments, is a planed finish with nothing else. So the skill of the carpenter or joiner with his plane is very important.

The expertly planed surface is a proven factor in longevity of wooden structures. Believe it or not, a carefully planed wooden column or beam lasts longer in an exterior location than a painted one (painting is obviously the most durable surface finish available for wood) by a factor of hundreds of years. This is because a painted finish always fails, peels, and powders with time. 30 years max? It must be constantly maintained and replaced. If water soaks quickly and deeply into the a hairy wood's surface, it causes differential expansion and cracking, providing wider paths for water to enter.

In the case of a planed surface, a bead of water is stable enough to span the gaps at the severed zylem conduits. But if the wood's surface is sanded, the hairs penetrate the bead, and will suck water into the grain. Dust collects on a surface regardless of the finish, but it sticks better to a hairy, sanded surface. Dust includes bacteria and mold and mildew and spores that are sucked in with the water, accelerating rot. So it is not an exaggeration to say that sanded surfaces cause the wood to rot relatively quicker.

A sharp blade is an absolute requirement, but beyond 6000 to 8000 grit, it doesn't make much difference in finish. A finer sharpening job does help the blade stay sharper longer. Interestingly, a highly polished blade takes more force to cut wood than a medium sharp blade.

Perhaps more important is an appropriately tight mouth with even pressure by the sole right up to the opening. Most people get this detail wrong. A true sole that doesn't rock is also important. A properly setup and installed chipbreaker is very important when cutting cross-grained wood. But when cutting with the grain, a chipbreaker does not produce a smoother surface than a single blade.

[Stanley Covington]

If your after a burnished finish similar to what's seen within that video, the hand plane your using for your final pass needs to have a wooden sole. A metal sole wont do it, regardless of how fine you set your shaving. Old school knowledge that wasn't restricted to Japan.

Stewie;

A metal plane will do it too.

[Warren Mickley]

Warren, those are the finishes I use as well with furniture. I'd use them in the kitchen if they were waterproof and resistant to heat, steam, etc. I'd rather use a finish I can rub on. I have little experience with spraying, and am happy to keep it that way. Any comments on the durability of the above finishes in a kitchen?

Derek

I would say the durability is somewhat technique dependent. I have a friend who put shellac on his kitchen table. A hot dish carelessly placed with no pad left a mark that had to be restored. However moisture has not been a problem. I have had a small table in the kitchen with shellac for 30 years; there have been lots of cold drinks on it without a problem. Try this: Put a tablespoon of water on a flat finish sample and see what happens over eight hours or so. Also put a sample over a steamy kettle.

One thing to keep in mind is that shellac can be repaired or refreshed a lot more easily than polyurethane.

[Stew Denton]

Hi All,

A few comments, responding to Fred's question, but made with trepidation, as I don't know as much about surface tension as I should. I hope to make a couple of comments of practical application for finishes. (But don't count on it. This may be chemistry filled and boring, so you have been warned and may want to quit reading now while you are ahead.)

That said, this is the 3rd time that I have tried to respond to this post, and the computer ate the first two long, chemistry filled, fiascos, and each try the post has gotten shorter with less chemistry.

To summarize what I wrote before as short as possible with a LOT less explanation as to "why", the water is strongly attracted to the wood surface. This is due to what we chemists call "hydrogen bonding" between the water and "hydroxyl groups" that cover the surface of the wood.

Water has a strong affinity for sugar because of hydrogen boding between the water the many hydroxyl groups on the sugar molecule, and because of that, sugar rapidly dissolves in water. Cellulose is polymerized sugar, it is a big component of wood, and just like the sugar it is made from, has lots of hydroxyl groups and also other oxygen atoms present. All of these are capable of hydrogen bonding with the water, so water loves cellulose, and hence loves wood.

Each water molecule, however, loves every other water molecule too. This is the cause of water's surface tension, which causes the water to form drops, and causes it to bead up, like it did on the right hand picture. The way to overcome the surface tension of the water is to maximize the attraction to something else, in this case the wood surface. Thus, the more surface area that the wood has, the more the water molecules will overcome their love for each other and flow onto the surface of the wood because of the maximized hydrogen bonding with the surface of the wood. This is like it did in the left hand picture.

The cleanly planed wood surface is cleanly sliced off, and leaves a flat clean surface with little roughening of the surface and few fibers. This means a minimized surface area, and thus the attraction of the water to the wood surface is minimized. Because of this minimized attraction to the woods surface, the water stays beaded up.

On the other hand, the sanded surface is relatively roughened, with shredded wood on the surface and many stray fibers. This gives a maximum surface area and thus maximizes the attraction of the water to the wood, and the water spreads out onto the wood surface like it did on the video. The big surface area of the wood overcomes the natural affinity that the water molecules have for each other, thus defeating the surface tension of the water, so the drop collapses and flows into and onto the wood surface.

The effect on finishing is in the following post.

Stew

[Mel Fulks]

Warren is certainly right. Easy enough and legally safe enough for all the modern finish makers to declare shellac too fragile. It was used by US government as a major component of coatings for wooden ship hulls through both world wars.
Fresh shellac is not fragile, in some tests I did ,it took days under water for some white to form on some blocks; after some hours the white clouding disappeared.

[Stewie Simpson]

What is Burnishing?

Burnishing is a finishing technique that is used on wood. It gives the wood a smooth, shiny finish similar to the appearance achieved when using polyurethane or lacquer.

Burnishing is a technique that is frequently used when professionals do not want to apply chemicals to their products. Burnishing is done by rubbing two pieces of wood together. The heat from the friction rubs away soft, dried cell walls and exposes the harder cells. These hard cell walls do not absorb stain or finishes, but they have a glossy sheen that makes finishing products unnecessary. Burnishing can also be done by rubbing small shavings or chips on the wood. Burnishing is often used when professionals do not have time for chemical finishes to dry, but they also use the technique to achieve a certain appearance. Burnishing is used for furniture, cabinets, floors and other items in the house.


Read more: http://www.kitchencabinetkings.com/glossary/burnishing/#ixzz4NmVuEHMf

[Stewie Simpson]

If your after a burnished finish similar to what's seen within that video, the hand plane your using for your final pass needs to have a wooden sole. A metal sole wont do it, regardless of how fine you set your shaving. Old school knowledge that wasn't restricted to Japan.

Its a subject I am familiar with;

http://i1009.photobucket.com/albums/af219/swagman001/water%20stone%20flattening/_DSC0187_zps2rwwo981.jpg (http://s1009.photobucket.com/user/swagman001/media/water%20stone%20flattening/_DSC0187_zps2rwwo981.jpg.html)

http://i1009.photobucket.com/albums/af219/swagman001/water%20stone%20flattening/_DSC0188_zps5zqz567k.jpg (http://s1009.photobucket.com/user/swagman001/media/water%20stone%20flattening/_DSC0188_zps5zqz567k.jpg.html)

[Derek Cohen]

I would say the durability is somewhat technique dependent. I have a friend who put shellac on his kitchen table. A hot dish carelessly placed with no pad left a mark that had to be restored. However moisture has not been a problem. I have had a small table in the kitchen with shellac for 30 years; there have been lots of cold drinks on it without a problem. Try this: Put a tablespoon of water on a flat finish sample and see what happens over eight hours or so. Also put a sample over a steamy kettle.

One thing to keep in mind is that shellac can be repaired or refreshed a lot more easily than polyurethane.

Thank you Warren. That is advice I shall follow. I mentioned the choices to my wife. Her comment was, "as long as I can wipe the surfaces down with a wet cloth". I've always like the fact that Shellac is so easily repaired and, although no one is particularly heavy-handed in the family, stuff happens.

I have another related question for all, but will ask it in its own thread.

Regards from Perth

Derek

[Derek Cohen]

Its a subject I am familiar with;

http://i1009.photobucket.com/albums/af219/swagman001/water%20stone%20flattening/_DSC0187_zps2rwwo981.jpg (http://s1009.photobucket.com/user/swagman001/media/water%20stone%20flattening/_DSC0187_zps2rwwo981.jpg.html)

http://i1009.photobucket.com/albums/af219/swagman001/water%20stone%20flattening/_DSC0188_zps5zqz567k.jpg (http://s1009.photobucket.com/user/swagman001/media/water%20stone%20flattening/_DSC0188_zps5zqz567k.jpg.html)

Thant looks like Western Red Cedar to me. Yes? I use it for windows and blinds, not furniture. I finish this with a Sikkens product against the WA sun. Not much need for a burnished finish (unless you mean "burnt" finish :) ).

I am curious to know what furniture you have made, Stewie. Any photos?

Regards from Perth

Derek

[Stewie Simpson]

Douglas-Fir. Commonly referred to as Oregon pine is Australia. http://www.wood-database.com/douglas-fir/

[Stew Denton]

Hi All,

To those few brave souls who put up with reading the first post.

What is the effect of all of this on finishing.

Well, if this works for water, it ought to work for finishes, right?

Whoa Nelly! There is a fly in the oatmeal. One problem is that water loves the wood surface, so water based finishes will wet the wood surfaces easily. However, many finishes are primarily hydrocarbon based, and hydrocarbons are hydrophobic, that means that are not attracted to water, and it also means that they don't have as strong an affinity for the hydroxyl groups of the wood than water based finishes are. Also, if the wood has not dried well, the water in the wood makes it even less attractive to the hydrocarbon type finishes. Finally hydrocarbon solvents, such as paint thinner, are also hydrophobic, and don't like water. However, if the wood is thoroughly dry, most finishes seem to adhere well.

Well, companies who make finishes do various things to overcome the surface tension of their finishes so they will flow out and "wet" the surface of the wood. I'm sure there are various approaches, but two of the most common are: 1. adding a surfactant to the finish to overcome the surface tension of the finish, which is much like adding soap to water, and 2. reducing the viscosity of the finish by adding solvents or "thinners."

Most older and modern finishes also have some hydrogen bonding capability.

Nitrocellulose based lacquer has a lot of atoms that will yield hydrogen boding and should be attracted to the wood.

Shellac is dissolved in alcohol, and thus must be quite polar and has lots of potential for hydrogen bonding. In addition, the alcohol is capable of hydrogen bonding and will "wet" wood quite well, helping the shellac to adhere strongly to the wood. In addition, the alcohol is very non-viscose, so it acts as both a thinner and a facilitator of hydrogen bonding with the wood.

Drying oils like linseed and tung oil both are fundamentally hydrocarbon based, but the oils have three "ester" linkages in the center of each molecule so can adhere well to wood, and in addition each has multiple double bonds that can crosslink and form very resistant polymers on the wood, in addition to soaking into the wood.

In short, finishes that can adhere to the wood by initially forming hydrogen bonding, and such that can be thinned down easily, without problems, such as shellac should adhere well. In addition shellac can be made with alcohol, and since alcohol likes things like wood and it is very thin, its might be a good choice.


Finally, with some finishes that don't always adhere well, sanding might help, having the wood thoroughly dry, and having the finish that can be thinned down some should help the finish to adhere.

Well, getting too sleepy to write or think. Time to give it up.

Stew

[Stewie Simpson]

Excellent post Stew.

[Stanley Covington]

Its a subject I am familiar with;

http://i1009.photobucket.com/albums/af219/swagman001/water%20stone%20flattening/_DSC0187_zps2rwwo981.jpg (http://s1009.photobucket.com/user/swagman001/media/water%20stone%20flattening/_DSC0187_zps2rwwo981.jpg.html)

http://i1009.photobucket.com/albums/af219/swagman001/water%20stone%20flattening/_DSC0188_zps5zqz567k.jpg (http://s1009.photobucket.com/user/swagman001/media/water%20stone%20flattening/_DSC0188_zps5zqz567k.jpg.html)

To burnish is defined as the act of making a material's surface shiny or lustrous by rubbing it. Most commonly applied to metal surfaces. Never heard of rubbing two pieces of wood together to make a shiny surface. I have often used a stiff brush to remove/recess soft summer wood leaving harder winter wood proud of the surface. This polishes the wood producing a shiny surface. How would you rub two pieces of wood together to finish kitchen cabinets or wood floors?

The surface we are seeing in the video is obviously not a "burnished" surface, it is a planed surface. Equally obvious is the fact that the miyadaiku planing the wood is not, at least at the stage shown in the video, trying to produce a "burnished surface." He intends to produce a planed surface.

So help me understand your point, Stew.

Are you suggesting that with each pass of his plane he was "rubbing" and/or "burnishing" the wood? With a single pass?

Or is your point that a shiny surface on wood can only be achieved by "rubbing" it with a wooden plane, and that a metal plane can't achieve an equally shiny or lustrous surface appearance? Really?

Or, is your point that, since its a subject you are familiar with, that you are unable to create a shiny or lustrous surface with your metal-bodied plane?

I think that most well-traveled people with both eyes and hands-on experience in both traditions recognize that the Japanese woodworking tradition in general is different, but not superior to Western traditions. A steel-bodied plane can, at least in my hands, and I am absolutely certain in the hands of many belonging to this forum, plane a nice piece of wood just as shiny and lustrous as a wooden-bodied plane finishing of any type in the hands of an expert can. Obviously. But your experience seems to be different. So share with us your experience on the subject of the inadequacy of steel-bodied planes for "burnishing" wood.

[Trevor Goodwin]

Douglas-Fir. Commonly referred to as Oregon pine is Australia. http://www.wood-database.com/douglas-fir/

I thought I recognized that timber! I've been using some of it to make a sawing bench, it planes beautifully and I love the smell it gives off. Unfortunately the stuff my local yard sells is pretty poor grade and every piece has heart running through it, so every piece has twist and cupping.

[Stewie Simpson]

Stanley; when I refer to the final pass, its the last plane used to prepare the timber surface.

Stewie;

[Marty Schlosser]

A few years back at a finishing symposium our association held, I wanted to encourage everyone to hand-plane their work and use sandpaper only when needed to knock off any problem areas such as have been mentioned by previous posters to this thread. The idea was that this could possibly save time. To prove my point, I ripped a 10" wide piece of american cherry in half. I gave one piece to Jacques Breau to hand plane and sanded the other half using my ROS. Whereas Jacques took about 1 minute to plane one face of his piece, I ended out having to go all the way down through successive grits to P2000 to achieve the same smooth surface. That took me about 15 minutes to accomplish.

The finish I usually apply (Target Coatings waterborne - alkyd varnish) call for sanding to between P220 and P400 in preparation for finishing (here's the link to their website: https://www.targetcoatings.com/wp-content/uploads/2016/03/TC_TechDataSheet_EM2000_R3.pdf) Hence, I don't see much need for sanding beyond that level, which is therefore quite quick to accomplish.

[Pat Barry]

Stan, in the video, do they state what the sanded finish represents with respect to grit? Also, do they indicate if it was sanded with the grain or with a random orbit sander? Thanks

[Wayne Lomman]

Interesting video but what is the point? Is the implication that planing is superior to sanding? To adhere to one or the other is closing one's eyes to half the world.

More to the point, what seems to be missed so far with finishing is the fact that planing, sanding, burnishing (and yes, you can burnish timber), sanding technique and whether to sand at all etc etc is part of the finishing process. A good polisher uses surface texture techniques to create the final effect. It is often necessary to use many variations in texture on a single piece of timber.

I'm not going to waste time telling you all the scientific reasons why colour, texture and finishes work the way they do. It doesn't matter why if you understand how. I have the rest of my life to ponder why. Cheers

[Brian Holcombe]

Interesting video but what is the point? Is the implication that planing is superior to sanding? To adhere to one or the other is closing one's eyes to half the world.

More to the point, what seems to be missed so far with finishing is the fact that planing, sanding, burnishing (and yes, you can burnish timber), sanding technique and whether to sand at all etc etc is part of the finishing process. A good polisher uses surface texture techniques to create the final effect. It is often necessary to use many variations in texture on a single piece of timber.

I'm not going to waste time telling you all the scientific reasons why colour, texture and finishes work the way they do. It doesn't matter why if you understand how. I have the rest of my life to ponder why. Cheers

I think what they're doing is showing the difference between the two. Those surfaces do respond that way when finished in those two different approaches, so if you want the finish to take on water quickly then sanding would be a better approach in that instance.

I build furniture and now starting to build shoji....I want my work to be repellant of water, so I prefer planing.

[Stewie Simpson]

God damn Wayne; your talking my language. Good to see there's still some old school common sense on this forum. Its the 1st time I have ever heard of a Finishing Symposium. Is that a byo, or is the beer supplied.

Stewie;

[Stanley Covington]

Stan, in the video, do they state what the sanded finish represents with respect to grit? Also, do they indicate if it was sanded with the grain or with a random orbit sander? Thanks


Pat:

No mention at all of how the wood was sanded. It is a disappointing video. I think it is part of a TV program intended to impress people who have never held a plane or sanded a board.

Stan

[Stanley Covington]

I think what they're doing is showing the difference between the two. Those surfaces do respond that way when finished in those two different approaches, so if you want the finish to take on water quickly then sanding would be a better approach in that instance.

I build furniture and now starting to build shoji....I want my work to be repellant of water, so I prefer planing.

Brian:

Wise choice. Sanded shoji would be disgusting.

Stan

[Wayne Lomman]

God damn Wayne; your talking my language. Good to see there's still some old school common sense on this forum. Its the 1st time I have ever heard of a Finishing Symposium. Is that a byo, or is the beer supplied.

Stewie;


Lets hope for beer supplied!
Cheers

[Stewie Simpson]

The penny just dropped Wayne, I just noticed your location. Excellent territory with quality craftsmen and fantastic local timber.

regards Stewie;

[Wayne Lomman]

Moved here 12 years ago and for the first time in our lives we don't want to move anywhere else. Have to spend too much time working in Adelaide though... Cheers

[Stanley Covington]

Interesting video but what is the point? Is the implication that planing is superior to sanding? To adhere to one or the other is closing one's eyes to half the world.

More to the point, what seems to be missed so far with finishing is the fact that planing, sanding, burnishing (and yes, you can burnish timber), sanding technique and whether to sand at all etc etc is part of the finishing process. A good polisher uses surface texture techniques to create the final effect. It is often necessary to use many variations in texture on a single piece of timber.

I'm not going to waste time telling you all the scientific reasons why colour, texture and finishes work the way they do. It doesn't matter why if you understand how. I have the rest of my life to ponder why. Cheers

The implication in the video, which is the starting off point for this thread, is that a planed surface allows less water to soak into it. No mention was made in the video of finishes, burnishing, texture techniques or variations thereof.

In my opinion, as someone that understand the language, its an interesting video as far as it goes, but it doesn't go very far. No point in expecting it to address finishes when it it is simply talking about a very narrow point: planing vs sanding.

Stan

[Normand Leblanc]

Lots of very interesting information in this thread.

One more question. Let's talk about gluing those surfaces. My feeling tells me that two planed surfaces glued together would be stronger than two sanded surfaces. When looking at the gluing area it seems to me that it should be the other way around, isn't it?

[Brian Holcombe]

Brian:

Wise choice. Sanded shoji would be disgusting.

Stan

Haha, indeed and along that same vain I left then unfinished.

[Paul Bent]

Stan, could you expand on the why's of this statement?

"A sharp blade is an absolute requirement, but beyond 6000 to 8000 grit, it doesn't make much difference in finish. A finer sharpening job does help the blade stay sharper longer. Interestingly, a highly polished blade takes more force to cut wood than a medium sharp blade."

[Joe Tilson]

Stan,
It may not be a very good video, but it sure got us some good information about wood reacting to the way it is worked.
Thanks guys, this is great!
Joe

[Stanley Covington]

Lots of very interesting information in this thread.

One more question. Let's talk about gluing those surfaces. My feeling tells me that two planed surfaces glued together would be stronger than two sanded surfaces. When looking at the gluing area it seems to me that it should be the other way around, isn't it?

I recall Fine Woodworking Magazine doing a comparative test of that subject a long time ago, back when it was a worth reading. My recollection is that the planed surfaces developed a stronger glue bond.

I agree with you. Planed surfaces definitely glue up stronger than sanded surfaces. I suspect the glue applied to sanded surfaces bonds to the sanding hair and does not penetrate as deeply into as many strong, undamaged zylem conduits as it does in planed surfaces. The glue bond is only as strong as the wood it bonds to, right.

Planed board edges feel like they glue up tighter than sanded ones, but it is just a feeling.

Stan

[Stewie Simpson]

Normand; you might find the following link of interest.

Stewie;

A note of caution on smooth surfaces: Burnished areas may be smooth, but will not bond. Burnishing causes the cellulose to change chemical characteristics and thus not bond to the polyvinyl alcohol portion of the wood glue. This can be tested by putting a drop of water on the surface of the wood, if it doesn’t soak in, the surface is burnished or sealed and should be sanded until cleaned of the burnishing. http://www.popularwoodworking.com/techniques/best-wood-glue-surface-smooth-or-rough

[Patrick Chase]

Stan, could you expand on the why's of this statement?

"A sharp blade is an absolute requirement, but beyond 6000 to 8000 grit, it doesn't make much difference in finish. A finer sharpening job does help the blade stay sharper longer. Interestingly, a highly polished blade takes more force to cut wood than a medium sharp blade."



The first part of the statement is pretty straightforward, and I agree completely: Beyond a certain point you get into diminishing returns, and incremental improvements in polish don't buy you any improvement in performance for real-world woodworking. This is basically the same argument I made in the debate about whether the LV honing compound is actually 0.5 um or not - 0.5 um is 20000-30000 grit (depending on system) and is so far into diminishing returns that it just doesn't matter.

I would add two caveats:


I'd specify the threshold in terms of abrasive particle size rather than grit, because there's such variation in grit systems. I think that the point of diminishing returns is usually around 1.5 um, which would be ~7000 grit in Sigma's system and ~10000 grit in Shapton's.
The point of diminishing returns depends on what you're doing. Some woods are more sensitive than others, and some applications are more demanding than others. Kesurokai is a notable example of a demanding application, though I personally don't think that counts as real-world woodworking. With that said, I don't think there's ever much woodworking benefit from going below 1 um.

The second part of Stanley's statement is more conditional IMO. The argument that medium sharp blades cut more easily than highly polished ones is usually based on "toothiness" or "micro-serration" (Stanley, is that where you were coming from?). In my experience that's valid in some cases, and not in others. It's validity is greatest if there's a slicing component to the blade's motion, such that the blade is moving across instead of just into each fiber when it cuts.

[Stanley Covington]

The first part of the statement is pretty straightforward, and I agree completely: Beyond a certain point you get into diminishing returns, and incremental improvements in polish don't buy you any improvement in performance for real-world woodworking. This is basically the same argument I made in the debate about whether the LV honing compound is actually 0.5 um or not - 0.5 um is 20000-30000 grit (depending on system) and is so far into diminishing returns that it just doesn't matter.

I would add two caveats:


I'd specify the threshold in terms of abrasive particle size rather than grit, because there's such variation in grit systems. I think that the point of diminishing returns is usually around 1.5 um, which would be ~7000 grit in Sigma's system and ~10000 grit in Shapton's.
The point of diminishing returns depends on what you're doing. Some woods are more sensitive than others, and some applications are more demanding than others. Kesurokai is a notable example of a demanding application, though I personally don't think that counts as real-world woodworking. With that said, I don't think there's ever much woodworking benefit from going below 1 um.

The second part of Stanley's statement is more conditional IMO. The argument that medium sharp blades cut more easily than highly polished ones is usually based on "toothiness" or "micro-serration" (Stanley, is that where you were coming from?). In my experience that's valid in some cases, and not in others. It's validity is greatest if there's a slicing component to the blade's motion, such that the blade is moving across instead of just into each fiber when it cuts.

Sorry, I missed Paul Bent's question. Thanks for your astute comments, Pat.

The "point of diminishing returns" Pat mentioned is indeed the key factor. I think too many people get carried away with sharpening, myself included. But I don't have any sure way of determining grit size down to the micron, and so can only use the grit size of my stones as a reference. Therefore, I gave a range of 6,000 to 8,000 grit. Your mileage may vary.

When under time pressure on a jobsite, however, there is often not the extra five minutes to polish a blade all the way to 10,000 grit, so one experiments with getting by with rougher grits, and compares performance and durability with finer grits. If the grit size is too rough, say 1,000 grit, the plane cuts poorly, producing a nasty surface finish, and the blade dulls quickly, in my experience. A blade polished all the way to 10,000 will stay sharp a little longer when planing clean wood (cleanliness is a big qualifier) than one polished to 6,000 grit, but it won't cut much better or leave a discernably superior surface finish. If the wood (including the board's ends and sides, for instance) has any dust or grit on it (which it always does on a jobsite), the 10,000 grit edge will dull just as quickly as 6,000 grit edge. So in these jobsite circumstances, spending the extra time and money (stones aren't free and neither is time) doesn't yield a good return on investment. Ergo, "diminished returns." Does that make sense?

The phenomenon of the force required to motivate a plane increasing with a corresponding increase in a blade's polish is not something I pulled out of my fragrant fundament. It has been measured in laboratory conditions. The companies that make the blades for the Superfinisher planes and huge paper shears love these studies because it relates directly to blade edge longevity (how often the blade must be sent out to be sharpened, and resulting downtime), cleanliness of the cut (ragged, striated edges do not make for a nice book or magazine), and electrical consumption, all things their customers pay intense attention to. I believe it is the same phenomenon that causes the coefficient of friction between two surfaces to decrease as the surfaces become more highly polished, but as the level of polish increases up to a certain point, that trend reverses and friction between the two surfaces increases.

I know this is counterintuitive, but it is still absolutely true.

I know about superfinishers not because I own or use them, but because I buy lots of products that have been finished using them for my construction projects here in Japan. I have seen the machines in operation, discussed them with their owners and the manufacturers, inspected the factories, and read the specs. I know about paper shears because my relatives own several huge CNC machines made in Germany, and I have played with them (a 2.8m x 300mm blade is scary, actually), read the specs, and spoken with the sharpening company, and read the sharpening literature. I am confident the same principles applies to equipment in other industries.

This is most evident in handtools in the case of the Ooganna, the really wide planes where the force required to pull them is significantly higher than a regular sunpachi plane. So, for the planes we normally use, this point may be interesting and even detectable, but ultimately unimportant.

The micro-serrations Pat mentions is not a factor I was thinking of. As Pat pointed out quiet correctly, serrations really make a big difference with a skewed or slicing motion. Just like a serrated bread knife. Regardless of the fineness of the grit used to sharpen/polish, metallic blades (vs. obsidian, for example) always develop serrations to some degree or another. But for planes without skewed blades, serrations don't help much IMO. A plane blade acts very differently than a knife or scissors when cutting, and is a tool where sharpness has a much larger impact on performance.

I hope this makes my previous post a little clearer, Paul.

Stan

[Stewie Simpson]

Patrick; only can only relate to my own experience. and that is if you don't work your way up to 12000 grit on the stones before stropping on the Pure Chromium Oxide Paste, you will gain little in additional sharpness to the cutting edge. Little is gained by from using the PCOP if your stopping at 8000 grit on the stones.

As for the Chromium Oxide Wax Combo Bar I had in my workshop, it was last seen in the garbage bin a fortnight ago. R.I.P.

regards Stewie;

[Stewie Simpson]

8000 grit. http://www.sawmillcreek.org/showthread.php?247955-Hindustan-Honing-Stone-(Country-of-origin-USA)

12000 (+) grit. http://www.sawmillcreek.org/showthread.php?247786-Whats-under-the-stone

Stewie;

[Patrick Chase]

Patrick; only can only relate to my own experience. and that is if you don't work your way up to 12000 grit on the stones before stropping on the Pure Chromium Oxide Paste, you will gain little in additional sharpness to the cutting edge. Little is gained by from using the PCOP if your stopping at 8000 grit on the stones.

As for the Chromium Oxide Wax Combo Bar I had in my workshop, it was last seen in the garbage bin a fortnight ago. R.I.P.

regards Stewie;

I've used 0.5 um CrO film (3M 061X, which is pure and very tightly graded), 0.3 um AlOxide film (3M 266X), 0.1 um diamond film (3M 661X) and 0.1 um diamond paste (PSI). They all leave a better looking edge than an 8000# waterstone. The 0.1 um diamond film and paste yield amazing smoothness even under high magnification.

All of that is arguably irrelevant, though, because what matters (or should matter) to a woodworker is how the *wood* looks after you work it with the edge. That's where I think that diminishing returns come into play, and that's the point Stanley made as well in his follow-up post.

As I said the last time this came up, I'm sort of OCD-ish about sharpening and I usually do go down to 0.5 um or so, but I don't see any difference in my results when I stop at 1 um instead.

8000# is 1.2 um in JIS-compliant systems (Sigma, Imanishi) while 12000# is ~0.8 um. You should be able to easily and completely remove the scratches from either using 0.5 um CrO. IIRC you use 8K and 12K natural stones though, so we may be talking about vastly different abrasive sizes and therefore scratch depths here. Yet another case where "grit" is a fairly useless measure.

[Phil Mueller]

Please help me understand the significance of this. I get the smoothness issue. If a build up finish is to be used, wouldn't the final "smoothness" be determined by the finish? I've never read about any finish adhesion issues planed vs sanding. So unless the piece is to be left unfinished, or perhaps just a penetrating oil used, is there any other advantage to a planed surface? Not an argument for or against, just trying to learn something here. Thanks.

[Brian Holcombe]

Phil I find that a nicely planed finish offers advantage. I can maintain panel flatness which is tough to do with an ROS. I can keep clean edges and nice chamfers. I can also work without dust, the finest sanding dust of course being incredibly dangerous to have floating in the air.

[Patrick Chase]

Please help me understand the significance of this. I get the smoothness issue. If a build up finish is to be used, wouldn't the final "smoothness" be determined by the finish? I've never read about any finish adhesion issues planed vs sanding. So unless the piece is to be left unfinished, or perhaps just a penetrating oil used, is there any other advantage to a planed surface? Not an argument for or against, just trying to learn something here. Thanks.

Correct, if you're going to build up a thick film then that will obscure the surface of the wood. In addition to the finishes you list I think that the difference is visible under thin films (as from oil/varnish mixes or shellac, for example).

[Derek Cohen]

In 2006, FWW mag ran an article in which surface were sanded vs scraped vs planed, and then finished with boiled linseed oil, oil/varnish, and shellac.

As expected, the surfaces favoured the planed finish before finish. However, they concluded that differences were difficult to detect after a finish was applied. The oil/varnish mixture was contaminated by sanding between coats, but the other finishes were compared as is. The woods used were close-grained Cherry and open-grained Mahogany.

You may need to be registered to open this link:

http://www.finewoodworking.com/membership/pdf/8877/011180064.pdf?fww_sid=NTc1NDQ4NTE0ODMzMzc3OTY4MzI2 MjcxNUE0NzY5NjQ4QjhBQ0REN0I5N0FCQjM4OTE4QUM0QUQyME IxREJBQzM4MUU4RkYzMUJBOTI2MTBFRjFDQjIwMjU4NDk3MzU3 fDE0NzcyNDMzNTA%3D&fww_token=75273c34bb7470da9d38c7c7e835158d

Regards from Perth

Derek

[Stewie Simpson]

If the wood surface is prepped to a burnished surface, it can adversely effect the seal coats ability to adhere correctly to the wood surface. The effectiveness of the seal coat has a direct impact on any other subsequent coats applied. No higher than 220 grit sanding is generally recommended prior to the seal coat. The burnishing effect that can be worked by a finely set smoothing plane has already been covered within previous posts. If your applying a penetrating oil finish, or wax finish, the above mentioned recommendations may not apply.

[Normand Leblanc]

If I understand you correctly Stewie, you are suggesting (post 51 and 61) to sand before gluing and to sand again before finishing if it's not oil or wax. This is assuming that a "burnished surface" is what we get with our planes.

The link you've posted in 51 does say that a burnished surface won't glue very well. In my experience (all my glue-up are prepared with a plane) I've never had a problem. Do you sand before gluing? Who's sanding before gluing?

Normand

[Stewie Simpson]

Normand; that's correct. 220 grit light sanding before adhesive is applied. Most of you have viewed the quality of the shellac finish I am able to achieve on my backsaw handles.

[Derek Cohen]

I do not deliberately sand to-be-glued joints or to-be-finished surfaces. Never experienced a problem with plane-polished hardwoods using oils or shellac. I do not use varnish/films, so cannot comment there.

Regards from Perth

Derek

[Patrick Chase]

I do not deliberately sand to-be-glued joints or to-be-finished surfaces. Never experienced a problem with plane-polished hardwoods using oils or shellac. I do not use varnish/films, so cannot comment there.

Regards from Perth

Derek

I think that the disconnect here is in the leap from "planed" to "burnished".

You're saying that you've finished plenty of planed surfaces without trouble. You're right. I've had the same experience using a variety of adhesives and finishes, including film finishes like poly and a variety of water-based finishes (like many people I use films when wear matters more than appearance).

Stewie pointed out that burnished surfaces present a bonding issue for both finishes and adhesives. He's also right, as everybody who's ever forced an overly tight M&T or dovetail and "bruised" the wood so that it won't absorb glue knows.

The thing is that typical smoothing doesn't leave a burnished surface. Planing usually leaves a surface in which the structure is relatively undisturbed and "open" to both adhesives and finishes. Stewie himself pointed out in post 19 in this thread (http://www.sawmillcreek.org/showthread.php?248244-Planed-Finish-VS-Sandpaper-Microscopic-View&p=2616105#post2616105) that burnishing only happens under fairly specific circumstances.

I have seen some degree of burnishing (though not enough to be an adhesion issue) where a rounded/cambered blade transitions from cutting to not cutting. The blade appears to apply a fair amount of pressure to the wood in that narrow transition area, and the resulting burnishing can be detected as a "shiny" band when the wood is examined under grazing light. That's why I try to keep the amount of corner relief of my smoothers less than the shaving thickness, though the tradeoff is that I have to align my strokes more precisely to avoid conventional tracking.

[Derek Cohen]

I think that the disconnect here is in the leap from "planed" to "burnished".

You're saying that you've finished plenty of planed surfaces without trouble. You're right. I've had the same experience using a variety of adhesives and finishes, including film finishes like poly and a variety of water-based finishes (like many people I use films when wear matters more than appearance).

Stewie pointed out that burnished surfaces present a bonding issue for both finishes and adhesives. He's also right, as everybody who's ever forced an overly tight M&T or dovetail and "bruised" the wood so that it won't absorb glue knows.
The thing is that typical smoothing doesn't leave a burnished surface. Planing usually leaves a surface in which the structure is relatively undisturbed and "open" to both adhesives and finishes. Stewie himself pointed out in post 19 in this thread (http://www.sawmillcreek.org/showthread.php?248244-Planed-Finish-VS-Sandpaper-Microscopic-View&p=2616105#post2616105) that burnishing only happens under fairly specific circumstances.

I have seen some degree of burnishing (though not enough to be an adhesion issue) where a rounded/cambered blade transitions from cutting to not cutting. The blade appears to apply a fair amount of pressure to the wood in that narrow transition area, and the resulting burnishing can be detected as a "shiny" band when the wood is examined under grazing light. That's why I try to keep the amount of corner relief of my smoothers less than the shaving thickness, though the tradeoff is that I have to align my strokes more precisely to avoid conventional tracking.

Patrick, in your link Stewie wrote ...

If your after a burnished finish similar to what's seen within that video, the hand plane your using for your final pass needs to have a wooden sole. A metal sole wont do it, regardless of how fine you set your shaving. Old school knowledge that wasn't restricted to Japan.

He is implying two things: firstly, that wooden planes burnish wood when they plane; secondly, that he has knowledge of this - personal experience?

In regard to item #1 - I use wooden planes equally with metal planes, and I do no see a difference in regards the finish. Neither burnish automatically in my experience.

In regard to item #2 - I have not seen any indications in the past from Stewie that he has had any interest in, or has built, furniture - his contributions to date have been solely about planes, saws and sharpening stones (which he has shown us very readily). Stewie, perhaps you might show us examples of joinery and finishes in your furniture.

If this sounds a little confrontative, it is. The fact is that Stewie has been making comments for some time that indicate that he knows more than we do, and so contradicts other posters, which I find unpleasant. I'd like to see some personal evidence, rather than quotes from the Internet. I am happy to retract my comment and apologise if he can.

Regards from Perth

Derek

[Warren Mickley]

There are so many weird statements in this thread it is hard to know where to start.

I prepared stick of wood for water testing using a Bailey smoothing plane taking shavings at 0.0002 to 0.0003 inches (maybe 5-8 microns). The iron was sharpened full bevel in less than 90 seconds. The frog and the mating part of the iron have not been "tuned" in the 35 years I have had them, and probably not touched in the last 100 years.

Water beaded up on the surface and remained for 10 minutes or more. Water beaded similarly on a section prepared with a beech trying plane taking 0.002 shavings (50 microns). A small portion was then abraded at 220 grit and 320 grit and a drop of water was absorbed in about 5 seconds.

A planed section was burnished using a small piece of smooth hardwood; this section absorbed water much faster than the clean planed area, but not as fast as the abraded area. This is the first I tried putting water on a burnished area; I have no explanation for the results.

There is no problem using water stains or glue on a finely planed surface.

I read the 2006 Fine Woodworking article on planed and sanded surfaces. At the time I noted on another forum that all of the samples tested, both the sanded and the planed, were given a light initial coat of finish and then sanded. The wood itself was almost certainly abraded also in this step, so it was no wonder that the samples yielded very similar results. They were all sanded. A friend of the author came on the forum and chastised me for being too rough on the author who he said was a young amateur. It is hard to believe anyone still makes reference to this study.

[Wayne Lomman]

In the real world of commercial cabinet and furniture making, you always finish the surfaces to be glued either by fine sawing or sanding, never planing either by hand or machine. This is absolutely critical if you expect the furniture to last beyond the minimum 10 year structural warranty to which I work. This has been a principle for way longer than the 40 years I have been in the industry because I was taught by guys who were old when I started. You can argue all you like over hand planing vs machine planing, but the bottom line is don't glue a planed surface. I'm sure everyone has examples of their work that are fine, but do you have at last count about 12,000 examples that have not failed (that's chairs, I can't count the other stuff)? If so, I want to hear about it because I love to learn new techniques, especially ones that save work. Cheers

[Brian Holcombe]

Wayne, have you glued a planed surface? Furthermore have you glued one that has failed? Can the failure be attributed to the surface finish?


I'm suspect of your conjecture, while I appreciate your experience I think you're speaking entirely from hearsay on gluing planed surfaces but feel free to correct me with your real world experience in doing so.

[Wayne Lomman]

Brian, yes I have. I have had the misfortune to work in shops where this was the norm. I also have had the good fortune to work in excellent workshops where gluing planed surfaces was almost a DCM offense. Cheers

[Brian Holcombe]

So you glued a planed surface, it failed, then you tracked it down to the planed finish and not the fitment or some other reason?

[Warren Mickley]

Wayne, I have been gluing hand planed surfaces professionally for four decades. I think the joints are a little less noticeable.

I certainly have had to repair chair seat joints that were not hand planed. Chair seats are particularly vulnerable to breaking because of the their use. Here in Pennsylvania the better makers use single plank seats to avoid these problems. A glued up seat is considered cheap. You do not speak for all professionals.

[Stanley Covington]

There are so many weird statements in this thread it is hard to know where to start.

I prepared stick of wood for water testing using a Bailey smoothing plane taking shavings at 0.0002 to 0.0003 inches (maybe 5-8 microns). The iron was sharpened full bevel in less than 90 seconds. The frog and the mating part of the iron have not been "tuned" in the 35 years I have had them, and probably not touched in the last 100 years.

Water beaded up on the surface and remained for 10 minutes or more. Water beaded similarly on a section prepared with a beech trying plane taking 0.002 shavings (50 microns). A small portion was then abraded at 220 grit and 320 grit and a drop of water was absorbed in about 5 seconds.

A planed section was burnished using a small piece of smooth hardwood; this section absorbed water much faster than the clean planed area, but not as fast as the abraded area. This is the first I tried putting water on a burnished area; I have no explanation for the results.

There is no problem using water stains or glue on a finely planed surface.

I read the 2006 Fine Woodworking article on planed and sanded surfaces. At the time I noted on another forum that all of the samples tested, both the sanded and the planed, were given a light initial coat of finish and then sanded. The wood itself was almost certainly abraded also in this step, so it was no wonder that the samples yielded very similar results. They were all sanded. A friend of the author came on the forum and chastised me for being too rough on the author who he said was a young amateur. It is hard to believe anyone still makes reference to this study.

Warren:

Thanks for going to the trouble to test water penetration and share the results with us. Exactly as one would expect.

I don't have access to my old issues of FW magazine, but I recall the article I referred to was published around 1978 to 1979. By 2006, FW was not worth reading, and I know nothing of the silly study you referred to. I applaud you for trying to correct the author.

Stan

[Prashun Patel]

Isn't a lot of what we see in that video due to the surface tension of water?

I know that water has a higher surface tension than oil and I think even ethanol. I thought in fact, this is why some people add a drop of liquid soap to water when using it as a lubricant for (ironically here ;)) wet standing. I would suspect that pva glue has additives to counteract the surface tension of water and cause it to penetrate. I experience oil finishes (even dreaded polyurethane) and shellac to adhere just fine to planed surfaces.

I wonder how one could reliably design an experiment that compares this effect. Just seems so hard to control for this over time...

"Stewie pointed out that burnished surfaces present a bonding issue for both finishes and adhesives. He's also right, as everybody who's ever forced an overly tight M&T or dovetail and "bruised" the wood so that it won't absorb glue knows."

Patrick, this is a curious statement that I hadn't considered before. in fact recently, I've been attempting to make my M&T and dovetails compression-fitting. I was under the impression that the better the fit in fact the less job the glue has to do.

[Pat Barry]

Warren's results for water droplet absorbtion, coupled with the original video, and Wayne's experience all indicate that better glue adhesion should be with a lightly abraded surface. There is then a disparity wherein the best glue-line appearance would be with a cleanly planed pair of surfaces but a stronger joint might not be the best appearance. Tradeoffs like this are always being made. I don't see why this doesn't compute for some.

[Paul Bent]

If my joints are to have the same sheen as a finished plane surface, then I have a long way to go up that steep, steep mountain.

[Mel Fulks]

I think I've seen tests ,or at least comments ,from glue mfg showing no benefit from sanding before gluing. They do say gluing should be done soon after surfacing in anything that has pitch that can move to surface.

[Brian Holcombe]

I definitely agree Mel, and I could not find anything on Titebond's website that suggested not planing or that sanding is required.

Also, if the glue were not able to do its job as effectively on a planed surface I would expect the glue line to be thicker, not thinner.

[Mel Fulks]

When gluing up something to be turned ,like large urns, I have sanded prominent lines from a planer gap. That operation needs TWO men: one to do the work and one to say "that ain't neccesary" while smoking a cigarette .

[Patrick Chase]

There is no problem using water stains or glue on a finely planed surface.

Indeed. IMO "water-based" finishes should actually be described as "water-soluble", because they contain a lot besides water. In particular they typically contain surfactants, which prevent beading and ensure even flow-out even when the surface is very smooth.

If you somehow managed to apply enough pressure to burnish the surface then there would be a problem, because burnishing alters the structure (pores etc) in a way that impacts finish/glue absorption. As I said in #65 I don't see that happen as a result of "normal" planing.

[Patrick Chase]

Brian, yes I have. I have had the misfortune to work in shops where this was the norm. I also have had the good fortune to work in excellent workshops where gluing planed surfaces was almost a DCM offense. Cheers

When you say "planed" what exactly do you mean?

The reason I ask is because I don't know of many commercial furniture shops using HAND planes any more. If you're talking about the other sort of "planing" then I could easily see how what you say might be true, as the rotary motion of the cutter puts a lot of pressure on the wood at the start of each revolution and would cause burnishing.

[Patrick Chase]

Warren's results for water droplet absorbtion, coupled with the original video, and Wayne's experience all indicate that better glue adhesion should be with a lightly abraded surface. There is then a disparity wherein the best glue-line appearance would be with a cleanly planed pair of surfaces but a stronger joint might not be the best appearance. Tradeoffs like this are always being made. I don't see why this doesn't compute for some.

I think we need to be clearer about what glue[s] we're discussing here. Aliphatic glues don't rely on "mechanical grip" to a rough surface, but instead penetrate into porous materials like wood. Honest-to-goodness burnishing of the sort you get when you bang a too-tight dovetail together closes the pores and is bad news for that reason, but as I've said a few times I don't think that normal finish planing causes significant burnishing.

EDIT: I think the sticking point here is in the step from "water doesn't absorb into freshly planed wood" (as per Warren's results) to "glue and water-based finishes won't work". As I remarked in another post, water-based glues and finishes contain surfactants and other additives to promote absorption and/or flow-out. In my experience they work well unless the surface of the wood has actually been crushed/burnished.

[Patrick Chase]

"Stewie pointed out that burnished surfaces present a bonding issue for both finishes and adhesives. He's also right, as everybody who's ever forced an overly tight M&T or dovetail and "bruised" the wood so that it won't absorb glue knows."

Patrick, this is a curious statement that I hadn't considered before. in fact recently, I've been attempting to make my M&T and dovetails compression-fitting. I was under the impression that the better the fit in fact the less job the glue has to do.

If you test-fit a joint that's really tight (to the point where you have to whale on it with a large mallet to close it) and then pull it back apart, you'll notice that the mating surfaces have become shiny where the fit is tightest. That shininess indicates burnishing, and tells you that the wood's pores have been closed off by crushing. Those spots won't absorb glue as well as they otherwise would, and won't adhere as well as a less-tightly fitting surface would.

As you say there's a balance between adhesive strength and mechanical strength in DTs. The optimum is a DT that fits together snugly, but not so much so that it burnishes or is susceptible to squeeze-out and starvation.

[Patrick Chase]

Patrick, in your link Stewie wrote ...

If your after a burnished finish similar to what's seen within that video, the hand plane your using for your final pass needs to have a wooden sole. A metal sole wont do it, regardless of how fine you set your shaving. Old school knowledge that wasn't restricted to Japan.

He is implying two things: firstly, that wooden planes burnish wood when they plane; secondly, that he has knowledge of this - personal experience?

If we extend Stewie maximum benefit of the doubt in interpreting his post (which I believe to be a basic courtesy), he only says that a wooden sole is necessary to cause burnishing. He doesn't say that wooden soles are always sufficient to cause it.

To be honest, the only sort of well-tuned plane that I would expect to apply enough pressure to cause honest-to-goodness burnishing is a Japanese jointer with a 3-contact-point setup. In that case all of the downward planing pressure is concentrated in those small contact points, and that could easily be enough IMO. Note that the 2-contact-point setup used for Japanese smoothers wouldn't leave a final burnished surface, because both contact points are before the blade - any burnishing is immediately removed.

Poorly tuned planes are a different matter. I've seen burnishing from blades with severe tip-rounding and consequently negative clearance, such that the blade has to be mashed into the surface to cut. In that case you end up with a small spot with very high pressure just behind the cutting edge, which crushes the wood structure. Normite planers can present similar issues.

[Brian Holcombe]

Dovetails are high risk for cracking before burnishing IMO. The guideline I run by is that it should 'squeak' during assembly but that you should not need to drive it home with the commander mallet. You should, however, need to seat the joinery.

I like to compress the shoulders lightly on certain joints.

[Mike Holbrook]

Interesting points being made here.

Maybe I am missing something but it seems to me that a "burnished" surface is quite different than a planed surface. The planed surface was cut by a very sharp edge that left the structure of the wood cells pretty close to the way they were. Sanding obviously roughs the surface, destroying individual cell integrity. It seems to me that burnishing would drive small pieces of wood tightly into the open cells. It would make sense that this surface would respond to water drop tests somewhere between the planed and sanded surfaces.

It would also make sense, at least to me, that attempting to glue two burnished surface might result in separation under pressure. It seems to me that the glue, in a burnished surface, would be more in the wood "dust" than attached to the more structurally sound wood cells.

I think some of the "best" surfaces I have seen were made by guys using drawknives. I would speculate that the reason is, using a drawknife to make, particularly chair spindles, teaches the user to see and even feel the layers of wood within the work. Making a tapered spindle requires a "feel" for cell structure to more precisely taper the spindle on all "sides". In some ways a drawknife can be adjusted in terms of cutting pressure, direction, angle....all during the cut. I'm not saying the entire surface done with the drawknife is "better", just individual cuts can be remarkably clean when done in exactly the correct direction grain wise.

[Wayne Lomman]

I'm lost in this topic. Too many people shouting at once. For those who have specific questions about my knowledge and experience, send me a message and I will start a new thread and put it out in public. Cheers

[Stanley Covington]

When gluing up something to be turned ,like large urns, I have sanded prominent lines from a planer gap. That operation needs TWO men: one to do the work and one to say "that ain't neccesary" while smoking a cigarette .

The classic division of labor and management, eh?

[Wayne Lomman]

Patrick, you are correct, not many commercial shops use hand planes. I have discovered on this forum that I don't fit any one category. My work is based on what works in a given situation to achieve the required result, not on ideology. Cheers

[Wayne Lomman]

The other consideration is the species with which one works. I almost exclusively work with old growth eucalypt timbers. As I have commented elsewhere, they are dense, interlocked, abrasive and tannin rich. Perhaps this colours my views.

To put it in perspective, when white invaders arrived in Australia, they discovered that their wood working tools didn't actually work. Thus was born the Australian tradition that imported timber is better. Cheers

[Stewie Simpson]

If we extend Stewie maximum benefit of the doubt in interpreting his post (which I believe to be a basic courtesy), he only says that a wooden sole is necessary to cause burnishing. He doesn't say that wooden soles are always sufficient to cause it.

To be honest, the only sort of well-tuned plane that I would expect to apply enough pressure to cause honest-to-goodness burnishing is a Japanese jointer with a 3-contact-point setup. In that case all of the downward planing pressure is concentrated in those small contact points, and that could easily be enough IMO. Note that the 2-contact-point setup used for Japanese smoothers wouldn't leave a final burnished surface, because both contact points are before the blade - any burnishing is immediately removed.

Poorly tuned planes are a different matter. I've seen burnishing from blades with severe tip-rounding and consequently negative clearance, such that the blade has to be mashed into the surface to cut. In that case you end up with a small spot with very high pressure just behind the cutting edge, which crushes the wood structure. Normite planers can present similar issues.

Patrick; you need to use them to fully understand the difference in surface quality. It doesn't show clearly within the link attached photo, but I can guarantee you all 3 of those English style wooden soled planes would show signs of being burnished from the timber they were being worked on. Do you honestly believe that the burnishing is being restricted to the soles of the planes. Your comments about burnishing being restricted to the 3 point contact of a Japanese plane lacks depth of understanding.

regards Stewie;


http://www.theenglishwoodworker.com/wp-content/uploads/2013/02/mouths.jpg (http://www.theenglishwoodworker.com/wp-content/uploads/2013/02/mouths.jpg)



They’re certainly as quick as any metal alternatives, and my wooden smoothing plane can take on anything a metal plane can, leaving a far superior finish. http://www.theenglishwoodworker.com/getting-the-gist-of-wooden-planes/

[John Stankus]

I need to go back and read the whole thread thoroughly, but this appears to be an opportunity to take a few scientific measurements to address some of the comments.
I have been planning on getting the Contact Angle Goniometer set up that a colleague bought but has since left the University. The Contact Angle Goniometer is an instrument that measures the surface energy and wetability. Should be able to measure both the different surfaces and using some standard surfaces measure the properties of some of the common finishes. I will also have to check with my buddies up in the engineering department and see when the new scanning electron microscope should be up and running. I don't think they have an Instron tester (measures the strength of the glued joints) but they may have a simpler tester that can get us the same info.

John
(teaching chemistry is my day job :) )

[Patrick Chase]

I realized after my post-storm earlier that there are multiple senses of "burnish", ranging from simply "polishing up" the wood to applying significant pressure (for example with a rod) to actually compress the grain/pore structure.

Since the topic of this sub-thread was finish and glue adhesion, let's be clear that we're referring to the latter sort of burnishing, that compresses the structure of the wood by crushing and thereby closes off the pore structure on the surface. The other form of "burnishing" does not significantly impact adhesion. Typical crush strengths of hardwoods perpendicular to the grain are on the order of 1000 psi, and about 10X that parallel to the grain. Even if we (very, very conservatively) assume that only 1% of the total sole area is initially in contact, even the smallest plane you show would require hundreds of pounds of downforce to compress and thereby close off the surface in a manner that impacts adhesion.

Stewie, this is consistent with what everybody else on this thread has told you: Planing with a flat-soled hand plane (even a wooden one, of which I have and use a couple) does not prevent glue/finish adhesion. While I don't doubt that you get terrific surface quality from your planes, it is physically impossible that doing so is actually closing off the structure of the wood, and so I don't believe that it is causing whatever finish/glue adhesion problems you may have experienced. I think that's also where Derek, Warren, and others are coming from.

[Stewie Simpson]

Patrick; your misunderstanding the logic. While a burnished surface may accept a pva glue, its bond strength long term is far less reliable than that generated by a wood surface that has been abraded. You like to drop names to support your case, well you can add Pat Barry and Wayne Lomman to my list. I could talk more about the long term reliability of applying a surface coating to a burnished wood surface, the likely causes of Peeling and Flaking of the top coat surface, and the likely ramification as a result of seasonal changes in the moisture level within the wood, but since your wanting to restrict the conversation to the OPs subject of a glued surface, I wont go there.

regards Stewie;

[Normand Leblanc]

I think that the sole area of a plane is much too large to burnish the wood surface as described by Patrick in post 93.

On the other end, it is the blade tip (which have a small area- the sharper the blade the smaller the area) that could be responsible for some more serious burnishing. I'm not saying that it's causing a problem for me with glue or finish.

Normand

[Steve Voigt]

Patrick; you need to use them to fully understand the difference in surface quality. It doesn't show clearly within the link attached photo, but I can guarantee you all 3 of those English style wooden soled planes would show signs of being burnished from the timber they were being worked on. Do you honestly believe that the burnishing is being restricted to the soles of the planes. Your comments about burnishing being restricted to the 3 point contact of a Japanese plane lacks depth of understanding.


Umm, what? Yes, the burnishing is restricted to the sole of the plane. The sole is burnished from being rubbed hundreds or thousands of times against wood. Whereas on the piece being planed, the blade is exposing freshly cut surface on every pass. Only rear half of the plane is rubbing against the piece being planed, exactly once; then that surface is removed on the next cut. Or not, if it's the last cut. It's not enough to cause burnishing. You might want to think it through before condemning people for lacking "depth of understanding."

[Stewie Simpson]

Normand; you will have to excuse me from this discussion, I was hoping to get some decent time in the workshop during daylight, and its just turned 1.30pm.

regards Stewie;

[Stewie Simpson]

Steve; I wouldn't expect any different from your response. Must go; workshop time.

regards Stewie;

[Patrick Chase]

Umm, what? Yes, the burnishing is restricted to the sole of the plane. The sole is burnished from being rubbed hundreds or thousands of times against wood. Whereas on the piece being planed, the blade is exposing freshly cut surface on every pass. Only rear half of the plane is rubbing against the piece being planed, exactly once;

Ironically the sole of the plane in the video that started this discussion probably didn't even touch the final surface. It was a Japanese smoother, and if it had the 2-contact-point setup typical of such planes then its blade was the only part that ever touched the freshly planed wood.

[Steve Voigt]

Steve; I wouldn't expect any different from your response.



If by that, you mean that I used logic and facts instead of word salad and innuendo, then I agree. Thanks for the compliment!

[Steve Voigt]

Ironically the sole of the plane in the video that started this discussion probably didn't even touch the final surface. It was a Japanese smoother, and if it had the 2-contact-point setup typical of such planes then its blade was the only part that ever touched the freshly planed wood.

That's true. And the difference between rubbing that surface once (as with a Western woodie) versus not at all might matter in the Japanese woodworking tradition, with its extreme attention to surface quality, but I doubt it would be noticed by most, and certainly would have no effect on glue adhesion or finish absorbtion.

[Stanley Covington]

That's true. And the difference between rubbing that surface once (as with a Western woodie) versus not at all might matter in the Japanese woodworking tradition, with its extreme attention to surface quality, but I doubt it would be noticed by most, and certainly would have no effect on glue adhesion or finish absorbtion.

Hear hear!

[Stewie Simpson]

Left it too late to spend more than 1 1/2 hours in the workshop. Installed some extra Laser Light roof sheeting last week to improve the natural lighting. Being a warm day outside, its as hot as a Turkish Sauna inside the shed. Earlier start needed next time.

Stewie;

[Stewie Simpson]

If by that, you mean that I used logic and facts instead of word salad and innuendo, then I agree. Thanks for the compliment!

Ease it up fella's, there are too many daggers being pointed in my direction.

If you don't like the message, that's fair enough, but there's no need to destroy the messenger. This is meant to be a friendly open forum where logical discussion takes place. Its not meant to be a Gladiator's Arena, where the victor looks to the Emperor of Rome for the thumbs up, or thumbs down.

regards Stewie;

[Kees Heiden]

Relax guys ;)

There seems to be a contradiction going on here. The surface needs to be wetted, otherwise the glue doesn't work so well. The same message comes from this paper:

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch09.pdf

They also show the droplet test (fig 9.1) , if the droplet stays balled up, the surface isn't good enough for a good gluebond. But at the same time the paper sais:
Experience and testing have proven that a smooth, knife-cutsurface is best for bonding (Page 9.4 at the top).

Now, we see the high droplet on the planed surface in the japanese video and how the droplet is a lot more smeared out on the sanded surface. What's up doc? How can they recommend a planed surface, while the droplet test sais otherwise?

When you watch the Japanese video very carefully, you will see how the droplet on the planed surface in fact DOES spread out. At 1:20 into the video the droplet has lost its very steep angle to the surface, indicating that water has penetrated the surface.

But the sanded surface seems to be even better in this droplet test, so why the advice to use planed surfaces? I think this is more about how a plane makes the surface very flat with very sharp corners. Sanding always dubs over the corners a bit. This leads to a more visible glueline. In strenght I doubt there will be much difference bewteen a 220 grit sanded surface and a planed surface.

Of course, the article talks about using electrical jointers, because that is what is being used in most professional shops. The danger here is working with dull knifes, which readilly burnish the surface, imparing the glue joint. Sanding after using a blunt jointer is in fact a very good idea. Even better would be using a handplane.

[Stewie Simpson]

The crushed and burnished surface inhibits adhesive wetting
and penetration. If the adhesive does not completely penetrate
crushed cells to restore their original strength, a weak joint
results.

Thanks Kees; appreciate the research.

Stewie;

[Kees Heiden]

Of course, we should add that such a crushed and burnished surface stems from tools (jointers and tablesaws) with dull blades and from very coarse abrassives like used on these big stationary belt sanders.

Handplanes with a sharp blade do not crush or burnish.

[Stewie Simpson]

Kees; with respect, if you go back to the OPs video, the water test proved the surface had reached a burnishing point without the use of a mechanical machine, such as a power jointer, tablesaw, or stationary belt sander.

I do appreciate the time taken by you to track down that resource material.

regards Stewie;

[Kees Heiden]

I explained in my post on the previous page that a good look shows how the droplet decreases in height over the length of the video. At 1:20 the angle between the surface and the droplet is certainly less steep. I think this makes the droplet test not so usefull in practical use. You need to take a very close look.

In the mean time, experience shows that a handplaned surface is no problem to get a good glue joint. The oldest in my own experience, my kitchen, has a lot of edge glued panels that saw a hand plane as the last tool on the surface of the joint. After 6 years it's still going strong. That's just one datapoint of course, but it shows that a handplaned surface is not a recipe for disaster.

[Pat Barry]

But the sanded surface seems to be even better in this droplet test, so why the advice to use planed surfaces? I think this is more about how a plane makes the surface very flat with very sharp corners. Sanding always dubs over the corners a bit. This leads to a more visible glueline.
This is exactly the point I was making earlier. It would be great if there was physical test data to back up the resultant physical strength though as so much discussion energy is concentrated on perceptions. I don't think Brian or Warren or other competent hand woodworkers NEED to abrade their cleanly planed surfaces prior to, for example, edge gluing two panels. I'm sure they will get perfectly acceptable and long lasting glue joints. For that matter, if a person is doing a similar task with a powered jointer I am also confident that the surface prep will also be plenty good for glue joint strength and longevity. Per the manufacturer, all that's necessary is a pair of clean and dry surfaces that fit tightly to each other and adequate glue, clamping pressure, and time in the clamps.

[Patrick Chase]

Relax guys ;)

There seems to be a contradiction going on here. The surface needs to be wetted, otherwise the glue doesn't work so well. The same message comes from this paper:

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch09.pdf

They also show the droplet test (fig 9.1) , if the droplet stays balled up, the surface isn't good enough for a good gluebond. But at the same time the paper sais:
Experience and testing have proven that a smooth, knife-cutsurface is best for bonding (Page 9.4 at the top).

Now, we see the high droplet on the planed surface in the japanese video and how the droplet is a lot more smeared out on the sanded surface. What's up doc? How can they recommend a planed surface, while the droplet test sais otherwise?

Pure water has very, very high surface tension (polarity and all that). Just about everything you can conceivably add to it reduces that surface tension considerably. The fact that water beads on or is slow to penetrate a given surface doesn't say much about "water-based" finish or glue. The people who formulate those know all about beading and penetration issues in general, and have a very large toolset at their disposal to deal with them.

I agree with your points about power tools (other than supersurfacers). The rotary motion basically pulverizes the wood at the start of each pass, and annihilates the surface structure of the wood. You do not want to glue or finish machine-cut surfaces (again with the exception of supersurfacers).

EDIT: Toned down.

[Pat Barry]

I'd like to see an equivalent SEM photo of the surface that comes of my Rigid planer, er pulverizer. LoL. Its not bad excepting the snipe.

[Joachim Schmidt]

I'd like to see an equivalent SEM photo of the surface that comes of my Rigid planer, er pulverizer. LoL. Its not bad excepting the snipe.

Here they are:

346375
These SEM Photos I have got from an Investigation of superplaners from a German University.
Translation:
from left to right, wood spruce
milled with sharp tool, (if planer or shaper was not mentioned)
milled with dull tool,
planed with superplaner.

Perhaps this will explain, why it is not a bad idea to plane the surface of joints with a handplane afterneath the jointer. Too they can explain the perception of depht of grain of a hand planed surface.

Hope this was helpful.

Joachim

[Frederick Skelly]

Thank you Joachim!

[Allan Speers]

I can plane some things with ease, others with supreme frustration. I'm in awe of those who can plane everything with ease. I approach each project with the intention of using no sandpaper, and then inevitably hit some vicious tear out and have to resort to it.


Card scrapers, grasshopper, card scrapers! :)

[Patrick Chase]

I'd like to see an equivalent SEM photo of the surface that comes of my Rigid planer, er pulverizer. LoL. Its not bad excepting the snipe.

I think that Joachim's post addressed your request. I've seen similar SEMs in the past (and maybe those exact ones, they look familiar) and have seen real adhesion problems when gluing machine-planed surfaces.

IMO the issue has more to do with the rotational nature of the motion than with any deficiencies of the blades. When you initiate a cut by penetrating the surface of a fibrous material like wood you will always cause some distortion/damage to its structure. The problem with planers and jointers is that they penetrate the surface about 100 times per inch, leaving a microscopic trail of destruction in their wake. Supersurfacers and hand planes avoid that by making one long, continuous cut.

[Curt Putnam]

Pure water has very, very high surface tension (polarity and all that). Just about everything you can conceivably add to it reduces that surface tension considerably. The fact that water beads on or is slow to penetrate a given surface doesn't say much about "water-based" finish or glue. The people who formulate those know all about beading and penetration issues in general, and have a very large toolset at their disposal to deal with them.

I agree with your points about power tools (other than supersurfacers). The rotary motion basically pulverizes the wood at the start of each pass, and annihilates the surface structure of the wood. You do not want to glue or finish machine-cut surfaces (again with the exception of supersurfacers).

EDIT: Toned down.

So are you saying that I should not face glue the boards out of my DW735? I'll be gluing up 4/4 soft maple to make 24" of bench top? That's a lot of surface for an old man to hand plane.

[Patrick Chase]

So are you saying that I should not face glue the boards out of my DW735? I'll be gluing up 4/4 soft maple to make 24" of bench top? That's a lot of surface for an old man to hand plane.

For vertical lamination of a solid benchtop it may not matter. Benchtop thickness is typically driven more by stiffness/bending than by strength. If a solid benchtop is thick enough to be an adequately stiff platform for woodworking, then it will be capable of withstanding far higher loads than it will ever see in use. That in turn means that you probably have a lot of bond strength margin.

To put this in perspective, Franklin specifies >3000 psi sheer strength (ASTM D905) for all 3 varieties of Titebond when gluing maple to maple. Assuming that you're making a 2" thick benchtop you would have ~50 square inch bonds, that can resist shear loads of tens of thousands of pounds. If you lose, say, 50% of that strength due to nonideal surface prep then it's going to be a nonissue.

Bond stength is more of a concern for joinery, for example the strength of a miter or lap joint is often determined by the glue. That's the sort of application where you would worry about using a machine-planed surface. You might also worry about bond strength if you're creating a weight-optimized benchtop structure, like a torsion box (the whole point of a hollow structure is to use less material for a given stiffness, which in turn reduces the amount of strength margin you have).

[Patrick Chase]

Card scrapers, grasshopper, card scrapers! :)

Indeed. Even with a good "hook" the surface isn't quite as nice as from a well-tuned plane, but it beats sandpaper by a mile.

[Pat Barry]

Here they are:

346375
These SEM Photos I have got from an Investigation of superplaners from a German University.
Translation:
from left to right, wood spruce
milled with sharp tool, (if planer or shaper was not mentioned)
milled with dull tool,
planed with superplaner.

Perhaps this will explain, why it is not a bad idea to plane the surface of joints with a handplane afterneath the jointer. Too they can explain the perception of depht of grain of a hand planed surface.

Hope this was helpful.

Joachim
Thanks Joachim. That center photo is definitely from a 'pulverizer'!

[Mel Fulks]

I don't know enough science to say Patrick is not right, but tests frequently show no problems with glued joints on planed wood. Without failures what concerns can there be? Machine planed surfaces vary a lot just from different steels. Even with the lowest quality steel ,which is the most used, the glue manufacturers only warn about joints glued on surfaces not freshly cut.

[Shannon Cuffe]

Hi guys, I have been watching this thread with keen interest. There has been quite a lot of good information given. I have been in the trade for 17 years. I have used a myriad of different timbers, glues and surface preps. Glues ranging from TB supreme, TB original, TBII and TBIII, polyurethane, koyobond, resorcinol, and urea-formaldehyde. regardless of how I prepare the mating surfaces, the only time a glue joint fails is when I am being a lazy numbskull and attempt to join two convex faces. The harder woods split at the ends everytime, usually within the first month. Softer woods seem not to care so much.

The only difference I have seen with particular surface preps are
- sanding = fat glue lines due to the dubbing of the edges
- sawing - occasional chipout on the bottom edge due to the sawing action (it can be planed/sanded away but it is just more work)
- handplaning = probably the best/thinnest glue line
- machine planing = very similar to a handplaned glue line. it is probably slightly fatter than a handplaned joint.

So I do machine planed joints more often than not because most other preps (for me) are another step after jointing on the jointer.

[Van Huskey]

It always intrigues me that the most hand tool oriented spend the most time dealing with the micro-science of woodworking.

Interesting discussion.

[Derek Cohen]

Gad, there is too much over-thinking here. The only time I have experienced a panel come apart at a handplaned edge is when I starved it of glue as a result of over-tensioning the clamps. 20 years of jointing with handplanes and only the single example. Glues used ran the range of Titebond products, including hide glue, and epoxy.

Regards from Perth

Derek

[Stewie Simpson]

Its an interesting dilemma, much more common on this forum than any other I regularly frequent. Its genesis imo started off with a long and heavy discussion on the merits of bevel up bench planes, then veered right with the expanded choice of alloy steels on offer within chisel and plane irons, then veered left to the benefits of synthetic over natural honing stones, to where we are at this given moment, talking about a machined surface vs hand planed surface vs a sanded surface. Its difficult to speculate with certainty what the next high focus agenda might be on the near horizon. Possibly the type of colour that the manufacturers spray their hand planes, and how that can make a huge difference to your woodwork. Could Engine Black be soon replaced by Canary Yellow. Cant wait. I need to stock up on the popcorn.

Stewie;

[Curt Putnam]

Patrick, Thank you for the clarification. Was nervous for a while.