MinWax water based, oil modified Poly.... huh?

[Will Blick]

I am using the above finish for some Maple 2" edging that will get lots of wear. I am brush applying the above Poly. I want a glass smooth final surface. A few questions....

1) for max scuff resistance, was this a good choice?

2) How many coats for max. scuff resistance? I would guess 5?

3) How important to sand between coats? If I want 5 coats total, for good solid thick finish, is it OK to apply all coats a few hours apart,.... (dries VERY fast here) then after thoroughly dry, sand from 220/320/600 to get the glass smoothness I desire?

4) I was planning on sanding with a little distilled water, mainly to reduce the dust... is this acceptable?

5) I assume always sand with hand block, not power sander such as Festool Rotex set on fine mode?

5) What the heck is "water based, oil modified"....it says water based, so why the words modified oil?

Sorry for all the questions :-(
TYIA

[Howard Acheson]

1) for max scuff resistance, was this a good choice?

*** An oil based floor finish will have more scuff resistance.

2) How many coats for max. scuff resistance? I would guess 5?

*** Number of coats has little to do with scuff resistance. Instead, it's a factor in how soon the finish will be worn through. For most finishes, 3 to 4 coats is sufficient. Follow the label on the product.

3) How important to sand between coats? If I want 5 coats total, for good solid thick finish, is it OK to apply all coats a few hours apart,.... (dries VERY fast here) then after thoroughly dry, sand from 220/320/600 to get the glass smoothness I desire?

*** Depends on the product. If the label says to sand, then sand. With some finishes you can recoat within few hours without sanding but need to sand if you wait longer than 8-12 hours. Have you gone to the Minwax website and looked up the application instructions? You will also reduce the gloss by sanding http://www.minwax.com/wood-products/interior-clear-protective-finishes/water-based-polyurethane.html.

*** Finish sanding after application can be problematic on floor finishes. It can make them too smooth and folks are likely to slip. Any sanding needs to wait for the finish to fully cure. This can be 3-4 weeks.

4) I was planning on sanding with a little distilled water, mainly to reduce the dust... is this acceptable?

*** No, you don't want to use water as a lubricant on waterborne finishes.
5) I assume always sand with hand block, not power sander such as Festool Rotex set on fine mode?

5) What the heck is "water based, oil modified"....it says water based, so why the words modified oil?

*** Again, go to the Minwax site and look at the info that product.

[Steven Hsieh]

I know oil base polyurethane that when you applied too many coats, it becomes brittle and tends to crack. But in water base I don't know.

In Minwax instructions says to use 220 grit, IMO 220 is too rough for between sanding
I use 320 lightly sanding

It says let dry for 2 hours between coats.

[John TenEyck]

If the product you bought was Minwax Polycrylic then you will not be impressed with its scuff resistance. It is very soft and easily damaged. There are several waterbased polyurethanes that are very hard and wear resistant (equal or better than solvent based products, IMO), but it's a little late for that now unless you strip off what you've put on. But in case you do, or for your next project, you might consider General Finishes Hi Performance Poly. It's very hard by itself, but you can add a catalyst to it that is supposed to increase the hardness even further.

[Phil Thien]

5) What the heck is "water based, oil modified"....it says water based, so why the words modified oil?


Miracle Whip? MW=MinWax, and MW=Miracle Whip. Can't ignore that, can you?

Try to find the MSDS and it may help. I've also found the people at Minwax to be very helpful when I called them.

Are you in CA by any chance?

[Rich Engelhardt]

it says water based, so why the words modified oil?

Miracle Whip? MW=MinWax, and MW=Miracle Whip. Can't ignore that, can you?



LOL! :D funny..


Oils are quite often added to waterborne materials to improve flow and adhesion and to maintain a longer wet edge.
IIRC, there's a certain percentage level where they have to declare the material as being oil modified. - when the oil becomes part of the carrier and not part of the resin.
i could be wrong there - about the reason - it's been over 30 years since I rubbed elbows with the chemists @ the plant and research lab.

[Steven Hsieh]

LOL! :D funny..


Oils are quite often added to waterborne materials to improve flow and adhesion and to maintain a longer wet edge.
IIRC, there's a certain percentage level where they have to declare the material as being oil modified. - when the oil becomes part of the carrier and not part of the resin.
i could be wrong there - about the reason - it's been over 30 years since I rubbed elbows with the chemists @ the plant and research lab.

Rich

I thought they just tint the poly to make it a warmer color?:D

[Will Blick]

John, it is not Polycrylic MM product, which is much inferior to this newer product.... its also about 2x the price, but well worth it...

This was my first use of this product, its relatively new, maybe a year old rep said... After a day of application, I am quite impressed with it....

Steve, you were right-on, 220 way to coarse between coats. 320 min. is about right, maybe 400... as the goal is only to scratch the surface so it can better adhere to itself.

Howie, I did speak to technical support from MW, sometimes helpful, sometimes bad information... hence my questions, sorry if you found them offensive. This IMO is the value of forums, seeking advise from others who may have already experimented... for example, MM tech and MM docs say 600grit after final coat, NO WAY... 0000 steel wool was the proper abrasive, anything coarser removed too much finish, cloudy appearance, and created excess dust. 0000 = Superb glass smooth CLEAR finish.... very happy with outcome, which is rare for me and finishes :-) Hence why I was seeking advise.

BTW, Lowes sells this by the gallon $46, very low price.

Based on tech rep, this product is the best of water based (barely any yellowing over time) and the best of oil based (application, drying, etc). Dry time here in the SW was 30 minutes... (directions claim 2 hrs, but dry here, but only 70 deg F) the key was, lightly brushing the piece every few 5 minutes where any build up occurred....in which case, the entire process goes very fast, and you barely need any final sanding....

MM makes the same product in a Wipe-On Poly... I tried that first, but rep advised me, it takes 3 coats of the Wipe-On, to equal one Coat of the Brush-on. I will save Wipe-on for intricate work or areas that will not get abuse, lesson learned :-)

So the "water based, oil modified" is a marketing term, what else is new... as it turns out, this is quite common to have oil in the Water based products, interesting...

[Howard Acheson]

>>>> If the product you bought was Minwax Polycrylic

No, the OP said he was referring to Minwax® Water Based Oil-Modified Polyurethane. http://www.minwax.com/wood-products/interior-clear-protective-finishes/water-based-polyurethane.html

[Howard Acheson]

>>>> sorry if you found them offensive.

What did I write that makes you think I found your posting or comment offensive? I certainly didn't intend that.

[Will Blick]

Prob. mis interpretation on my behalf....

Before applying the poly, what is finest grit paper you should sand to?
I remember Howard mentioning anything finer than 150 grit would make the finish harder to adhere too.... make sense... did I recall this accurately?

[Steven Hsieh]

Prob. mis interpretation on my behalf....

Before applying the poly, what is finest grit paper you should sand to?
I remember Howard mentioning anything finer than 150 grit would make the finish harder to adhere too.... make sense... did I recall this accurately?

150 grit is too coarse
I think you meant 320 grit.

[Scott Holmes]

Before appling poly (varnish) meaning raw wood; I would say anything finer than 220 is wasting time and sandpaper. Between coats 220 or 320 is about right.

Of course I don't use poly on anything but floors... so, I use 80 or 100 on raw wood and 120 between coats.

[Howard Acheson]

Here is some info about sanding grits and sanding of both the wood and intermediate finishing steps.

Sanding wood--hard or soft--beyond 220 does little more than burnish the wood making staining difficult. This is particularly true if you are using a pigment stain which sits on the surface and relies on "nooks and crannies" to impart color. Softer more porous woods can be sanded to to 220 but harder less absorbent woods may stain best if only sanded to 150. The best compromise is to aim for 180 grit.

A number of years ago a large cabinet/custom furniture shop I was involved with did series of adhesion tests with various finishes and sealers. As part of this test we explored adhesion based on sanding grit. We found about the same adhesion up to 180 - 220. Beyond 220 adhesion dropped off due to burnishing of the underlying wood particularly when non-linear machine sanders were used. This was tested on birch panels. We also found that the resulting smoothness of the first coat of finish was not materially affected by the smoothnes of the underlying wood for sandpaper grits between 150 - 220.. The smoothest surface substrate for final finishes was obtained by sanding lightly after the first coat of finish was applied and dry. Which makes the case for a thinned first coat of finish.

So our conclusion was that sanding beyond 180-220 was not necessary and could be actually detrimental.

But, most important was that there was a big appearance affect if the surface was not HAND sanded in the direction of the grain using the highest grit used on the sanding machine. A flat pad sander produced a much flatter surface than a ROS. However, both required final hand sanding with the grain for optimum appearence. If not hand sanded, swirl scratches could show. Final hand sanding using a sanding pad in the direction of the grain is a must.

To carry it one step further, sanding at 320-400 grit after the first coat and subsequent coats was the optimum. No improved appearence was noticed by between coat sanding beyond 400 for varnish. 400 was the sweet spot for thinner finishes. Between coat sanding was always done by hand whether for flattening or for adhesion.

I think you will find similar thoughts in the popular finishing books but YMMV.

Finally, the first coat of ANY finish will soak little shards of wood and cause them to raise whether the surface was sanded, planed or scraped. When the first coat of finish dries these hardened shards are what causes the surface to feel rough. Sanding with 320 paper will remove these hardened shards and subsequent coats will go on smoother. So, smoothness counts after the first coat of finish, but not much before that.

The machine finish determines the starting grit. Jointers, planers, belt sanders etc, should leave a finish that allows starting with 100 grit. From there, go to 120 grit and sand until the marks from the prior grit are gone, then move to 150 and finish at 180 grit.

Plywood is factory sanded to 180 grit. Therefore, it's best to not sand plywood except with 180 grit and sand by hand. Get the first coat of finish on and then sand with 320. That way you are sanding the finish, not the wood. This avoids sanding through today's very thin surface veneer.

[Steven Hsieh]

Scott

On floors.

Do you use 120 grit sanding screens and hand sand?

[Will Blick]

great post Howard, thx.... so I did recall this low grit accurately.....
but its nice to have all these details in one place...

so, is there ever a reason to sand raw wood to say 400 grit?

Also, if you hand plane with ultra sharp blades, the raw wood is glass smooth. Like no sandpaper will ever achieve...what grit equivalent would you think this is equal to? and after hand planing on edging, with such a glass smooth surface, before applying finish, I assume the only sensible thing to do is sacrifice your glass surface and scratch it up with 180 grit b4 applying finish, right? That hurts, but I am assuming you will concur...

[Howard Acheson]

>>>> so, is there ever a reason to sand raw wood to say 400 grit?

**** Some who are applying a pure oil (ie: real, pure tung oil, boiled linseed oil) as their only finish will sometimes sand to 400 grit. In other words they are applying a finish that is totally absorbed into the wood therefore there is no need of adhesion as with a film finish. But, I would recommend instead that the oil be applied with 400 grit paper sanding it in and then wipe it dry.

>>>> Also, if you hand plane with ultra sharp blades, the raw wood is glass smooth. Like no sandpaper will ever achieve...what grit equivalent would you think this is equal to? and after hand planing on edging, with such a glass smooth surface, before applying finish, I assume the only sensible thing to do is sacrifice your glass surface and scratch it up with 180 grit b4 applying finish, right? That hurts, but I am assuming you will concur...

**** There is no issue with burnishing when sanding or scraping so there is no impediment to the adhesion of the finish with a planed surface. So you can apply your finish directly onto the planed surface.

Of interest is that a magazine ran a little test a few years ago. They sanded a board to 220 grit in one section, then scraped another section and planed a third section. The appearance of each section at that point was quite obvious and different. The planed surface appeared much "smoother". They then applied one coat of varnish thinned 25%, let it dry and then lightly flat sanded all sections with 320 paper on a cushioned sanding block. They then applied another full strength coat and let it fully dry. Next they had everyone in the shop look at the board and try to identify which areas were sanded, scraped and planed. They even brought in their office staff. None could discern any difference in the three areas after the finish was applied. The conclusion was that whether sanded, scraped or planed, they all looked the same after being finished.

[Scott Holmes]

Steve,

When I must sand beteween coats on a floor, I use 120 grit screen 1/2 sheet sander that's sold for sheetrock sanding and stick it on a broom handle so I can stand while sanding.

Will, sanding raw wood to 400 grit will burnish the wood and can cause finishing problems. I concur on the glass smooth wood after a razor sharp hand plane could cause finishing glitches; 220 is OK and doesn't hurt as much...

[Will Blick]

Scott, if I understand your post.... you suggest a glass smooth surface from a hand plane is problematic. It should be roughed up with 220 grit before applying finish... right?

Howard, you are stating the opposite.... I think....

or maybe there was a typo, or my comprehension is fading... I am very curious about this...

[Howard Acheson]

The result of using a very fine sandpaper grit--particularly if you use a powered sander--is burnishing the surface which can cause aborpsion and adherence problems. Burnishing is caused by the heating up of the wood causing an extraction of moisture that ends up sealing the surface of the wood. It really has nothing to do with the smoothness of the resulting surface. Planing does not heat up the wood it just shears off the wood. Therefore, there is no heat to seal the wood.

I will say however, that there is no advantage to achieving a planed surface. As the tests in the shop I reported about showed, there was no adhesion benefit to sanding wood to more than 220 grit--in fact sanding to 180 grit was just fine also. Additional smoothing beyond 220 grit did not resulit in a smoother finish after the finish was applied. The application of any finish is going to "raise the grain" requiring smoothing and leveling after the first coat no matter that a plane was used or it was sanded.

The bottom line is that sanding after planing is not going to affect adhesion. BTW, the "planing" I am referring to is hand planing. Surfaces run through a machine jointer or machine planer certainly need further surface preparation.

[Jack Clark]

Of interest is that a magazine ran a little test a few years ago. They sanded a board to 220 grit in one section, then scraped another section and planed a third section. The appearance of each section at that point was quite obvious and different. The planed surface appeared much "smoother". They then applied one coat of varnish thinned 25%, let it dry and then lightly flat sanded all sections with 320 paper on a cushioned sanding block. They then applied another full strength coat and let it fully dry. Next they had everyone in the shop look at the board and try to identify which areas were sanded, scraped and planed. They even brought in their office staff. None could discern any difference in the three areas after the finish was applied. The conclusion was that whether sanded, scraped or planed, they all looked the same after being finished.

Howard, do you recall which magazine? I'd like to try and find that article.

Thanks

[Will Blick]

Howard, thx for nice clear response... its burnishing (heat) that is the culprit, I did confuse this with surface smoothness....
Now I can use my hand planes with no guilt...

While you are tuned into this thread... maybe you can comment on these two issues...

1) MinWax does not NOT recommend spraying any of their finishes / stains. With small pieces, where time savings is not an issue, can you explain in what applications spraying is the preferred method of applying a finish?

2) Is there a reference on the web, which identifies the pros / cons of each finish...sort of a "help me select the right finish for this project" ...... I assume someone must have prepared a check list, or something?

thx in advance...

[Howard Acheson]

Minwax caters to the DIY woodworker/finisher. Spray equipment is not the way the majority of their products are used. Of course, no one recommends spraying oil based finishes. Oil based finishes dry very slowly. The over spray is in the form of liquid droplets that do not dry and will land on everything in the area creating a crust that is impossible to clean up. Spraying oil based finishes should only be done if the finisher has a good spray booth or sprays outside.

Another problem is that finisher formulate their products to comply with various VOC requirements. Spraying loads the atmosphere many more VOC's than brushing. So to keep their products in compliance the manufacturer will not recommend spraying or thinning of their products. Spraying finishes also entails health issues that manufacturers do not want to deal with. A final issue is that many amateur sprayers are not practiced or experienced. They do not set up their equipment properly, they do not thin or prepare the finish properly and they do not use good application techniques. The manufacturer has little or no control over the user and any problems get blamed on the product rather than the user. For a mass marketer, it's not worth the problems.

If you are looking for info on finishes and finishing, there is no better source than Flexner's Understanding Finishing and Jewett's Taunton New Complete Guide to Finishing. Amazon will have them. Get both if you are really looking to improve your finishing.

[Jack Clark]

I think I found the article Howard referred to. It was in Fine Woodworking. You can download the pdf here:

http://www.finewoodworking.com/SkillsAndTechniques/SkillsAndTechniquesPDF.aspx?id=24966

[Steven Hsieh]

Howard

I have couple of questions about varnish.


General Finish "Arm-R-Seal" and "Salad finish" are both same thing, they both have same ingridents (urethane resin).

How are they different compare to floor finishes like Pratt & Lambert "Varmor", Minwax fast drying, Varethane, Bona Woodline Poly?

Minwax has a 51% content and the P&L has a 48% urethane content.

[Howard Acheson]

I think I found the article Howard referred to. It was in Fine Woodworking. You can download the pdf here:

http://www.finewoodworking.com/SkillsAndTechniques/SkillsAndTechniquesPDF.aspx?id=24966

That's impressive Jack. That was 6-7 years ago. I checked my copy of FWW and the complete article is in there. It can only be viewed on the FWW forums by paid members. But one can sign up for a two week trial. Just be sure to go back in and cancel the subscription otherwise you automatically become a fully member--and will be billed.

[Howard Acheson]

>>>> General Finish "Arm-R-Seal" and "Salad finish" are both same thing, they both have same ingridents (urethane resin).

I don't know that to be true but all oil based varnish (poly is a varnish) have the same ingredients. Varnish is made by mixing and heating a resin (could be alkyd, phenolic or urethane or combination) and a drying oil (typically linseed oil, soya oil or sometimes tung oil) until the two become a new compound called "varnish". The varnish is the thinned so it can be brushed or sprayed.

There are a number of variables that the manufacturer plays with to result in a product that meets the performance characteristics the manufacturer wants to sell. Interior varnishes are typically harder so they contain a higher percentage of resin to oil. Conversely, exterior products are softer and more flexible so the resin to oil percentage is lower. Of course, exterior products will also contain some amount of UV protectorant. In addition, there might be flatters to reduce the sheen. Floor finishes may also have some added to reduce the slipperiness. They will also vary the amount of thinner depending on whether they are producing a brushing product or a wiping product.

Every manufacturer has their own formulas which they consider proprietary. Looking at MSDS can sometimes be helpful but manufacturers are only required to list dangerous or hazardous ingredients. So typically on a MSDS for oil based finishes you will only find the thinner(s) listed.

[Steven Hsieh]

From Bob Flexner book, he said that urethane is susceptible to UV damage.
But did not say if its heat resistance indoors. I know that polyurethane is water resistance.

Does this mean when all three resins are combined, it is water and heat resistance?
Like Arm-R-Seal for example.

Or is it just polyurethane and alkyd?

[Howard Acheson]

Yes urethane (poly, polyurethane all the same thing) is easily and quickly damaged by UV from sunlight even if the manufacturer claims it to contain UV inhibitors. Urethanes will quickly turn yellow, become opaque and begin to crack and peel.

Urethanes are slightly more heat resistant than non-poly varnishes but not by much. Depending on the product, maybe 10-20 degrees more tolerant. Basically, any oil based finish begins to soften and fail somewhere between 140 and 180 degrees. Combining resins in the manufacture of the finish will not make much of a difference. In general, urethane resins are cheaper than alkyd and phenolic resins so manufacturers will prefer to use them particularly for consumer grade big box brands.

"I know that polyurethane is water resistance." Are you referring to a polyurethane finish or a polyurethane resin? The type of resin used in the product has little affect on it's water or moisture resistance. Finishes made with urethane resins are not any more water resistant than finishes made with alkyd or phenolic resins. The much bigger determinate of water and moisture resistance is the oil used in manufacture. Tung oil is slightly more water and moisture resistant than linseed or soya oil so you will find the better marine exterior finishes are made with tung oil.

The number one objective for a finish manufacturer when formulating an varnish for use in exterior or marine applications is dealing with the large changing environmental conditions which can play havoc with adhesion. This means they will formulate with a higher percentage of oil to resin to make the resulting finish more flexible and softer. The means an exterior varnish is not as durable or abrasion resistant as an interior rated varnish. Also, the higher percentage of oil means that the finish will not be a water or moisture resistant which seems to not make sense for an exterior finish. But, remember, it's much more important for the finish to remain adhered that it is to have maximum water and moisture resistance. No one part oil based varnish is totally water or moisture resistant anyway.

I'm not sure about your reference to Arm R Seal. That product is just a urethane and linseed oil varnish. It's fairly highly thinned to allow it to be used as a wiping varnish.

So the bottom line is that all finishes are a compromise. Some are formulated for a particular application. I much prefer a non-poly varnish. Poly tends to be somewhat cloudy and plastic looking. It's fine for high use potentially abusive applications like everyday kitchen tables, hall tables that will have keys thrown on them or for floors. For funiture a good non-poly varnish will look nicer.

[Steven Hsieh]

Howard
Thanks for your help.

Thats the problem, most manufacturers dont tell you what Percentage of resin, type, etc... You will need to know.


From Steve Mickley(hardwoodlumberandmore.com)
He said that:

linseed oil-based varnish made with urethane resin (Polyurethane), soya oil-based varnish made with alkyd resin and tung oil-based varnish made with phenolic resin.

Is that correct?


I'm not sure about your reference to Arm R Seal. That product is just a urethane and linseed oil varnish. It's fairly highly thinned to allow it to be used as a wiping varnish.For that particular product, it is urethane cooked with linseed oil to make it varnish?


Poly tends to be somewhat cloudy and plastic looking. It's fine for high use potentially abusive applications like everyday kitchen tables, hall tables that will have keys thrown on them or for floors. For funiture a good non-poly varnish will look nicer.Thats why manufacturers don't use it for kitchen cabinets and bathrooms such. Lacquer is used instead ,more easier finish to repair and more resistance to water?


What is the difference between the 1-part varnish and 2-part varnishes?

[Howard Acheson]

Most urethane varnishes are made with linseed oil. Alkyd varnishes are made with linseed oil, soya oil or tung oil, phenolic varnishes are made with linseed oil or tung oil.

Cabinet manufacturers don't typically use oil based products for kitchen and bathroom cabinetry because it takes too long to dry and fully harden. They need to push the job out of the door to make room and to get paid. NC lacquer is less water and abuse resistant than oil based finishes but is easy to spray. Most cabinet shops are moving to catalyzed (2 part) lacquers. These lacquers are more water and abuse tolerant than oil based but require professional skills and equipment to apply.

All oil based finishes are made by "cooking" a resin and an oil.

Two part polyurethanes are used primarily in marine applications. They are harder and considerabley more water resistant. They are also for professional use and are quite expensive. There is little use for them in the consumer trade.

I suggest you buy a copy of Bob Flexner's Understanding Finishing if you don't already have it. It will answer almost all your questions about finishes and finishing.

[Steven Hsieh]

Howard
After asking all you these question, it makes no point of doing it.:D
With strictly V.O.C law, no solvents will be used anymore.

I have Bob's Flexner book,
There are some things that you said is not in the book.