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Richard Dooling
06-10-2009, 4:32 PM
Are all green honing compounds pretty much the same? I ask because when I use the compound I got from Wood Craft, I get sort of a dull finish. It's plenty sharp but not polished like a mirror.

Jim Nardi
06-10-2009, 7:27 PM
More chromium=more money and you need to know the particle size. 0.5 seems to give the perfect polished edge IMO.

Sean Hughto
06-10-2009, 8:19 PM
Never tried any other than Lee Valley's. Never had any complaints about it. In fact, I think it works great. I don't remember looking for mirrors though. I just wanted sharp.

Derek Cohen
06-10-2009, 9:50 PM
Hi Richard

My take on this - only having used the LV green rouge (and very happy with it) - is that the chromium should produce a mirror edge. When it does not, then I assume that there are "impurities" in it, these being grits that are greater in size than .5 microns.

The situation is similar to the results produced by natural waterstones. The end result is typically misted but still no less sharp. Fine natural waterstones may break down into very fine particles - some less than .5 microns - but there will be other grits within the stone that resist this and are responsible for creating scratches that are too deep to be removed by the remaining media.

This is less likely to occur in man made waterstones since there is greater control over the contents. The more expensive the stones/rouge, the likelihood is that there are better controls when manufactured (which is a more expensive product in the end). Is this a case of you get what you pay for?

Regards from Perth

Derek

Jim Koepke
06-10-2009, 10:42 PM
Is this a case of you get what you pay for?

Regards from Perth

Derek



Don't you just hate it when they start enforcing that law?

jim

James Scheffler
06-10-2009, 11:40 PM
Are all green honing compounds pretty much the same? I ask because when I use the compound I got from Wood Craft, I get sort of a dull finish. It's plenty sharp but not polished like a mirror.

I get a dull finish when I use green compound I got from Grizzly. I've assumed that it's just residue from the wax compound medium. It definitely works to make the blade considerably sharper, so I just haven't worried about it.

Jim

Aaron Kline
06-12-2009, 5:08 PM
If the blade is sharp, does it matter if the bevel is shiny? I used the cheapest green compound I could find and my blades will pop the hair off my arms and they are not the slightest shiny on the bevel.

Richard Dooling
06-13-2009, 11:16 AM
I have to admit this is taking things a bit far but a mirror surface must be smoother than a dull surface. A dull surface is dull because the light is being scattered by surface irregularities. A shiny surface is shiny because the surface is microscopically so smooth that parallel light rays remain parallel when reflected off the surface.

Of course you can have nice shiny metal leading up to a nicked or dull edge. But a mirror surface on the back and the bevel presents the opportunity to have a sharper edge because there are fewer surface irregularities.

Will I notice a difference in the force required for a given cut – I doubt it. But if all I need to do is switch out honing compounds or modify my technique then what the hay. Heck, I’m just having fun.

Now if I can just get better at establishing a consistent blade camber.:rolleyes:

.

george wilson
06-13-2009, 1:10 PM
I tried to make the case that a shiny edge must be sharper months ago. Curiously,some po-poed the concept.To me it seems perfectly logical.

Why don't some of you try stropping with Simichrome,or Flitz as an abrasive?

David Keller NC
06-13-2009, 1:24 PM
"I have to admit this is taking things a bit far but a mirror surface must be smoother than a dull surface. A dull surface is dull because the light is being scattered by surface irregularities. A shiny surface is shiny because the surface is microscopically so smooth that parallel light rays remain parallel when reflected off the surface."

This is not technically correct. All other things being equal, a surface that has smaller imperfections will reflect more light than one with bigger imperfections. However, all other things aren't equal. The luster (and therefore the appearance of a "Mirror Polish") is heavily dependent on the metallic composition and/or microscopic residue on the surface - neither of which will necessarily have any impact on sharpness.

One example is comparing the luster of some of my blades when worked on a coarse, then very fine diamond stone prior to final honing on an artificial 8000 grit waterstone. The blade is bright silvery coming off of the diamond stone, and definitely has the aspect of a mirror, though a somewhat hazy mirror, off of the very fine side of the diamond stone. Off of the waterstone, the back is a very clear mirror, but a very dark one - the overall appearance is a dull gray. I also have blades made of cast steel that are this dull gray color regardless of whether they're coming off of the diamond stone or the waterstones, and I have other antiques that have the silvery-bright appearance off of the same stones.

The point here is not that one can't use the reflection off of the back of a blade as a guide to whether or not more work is needed on an individual stone, but trying to compare one blade to another or one stone/stropping compound to another solely on the degree of "shinyness" is not a valid comparison.

In the end, you can't get away from testing the blade on an end-grain scrap of softwood if you want to know if it's truly sharp, though there's one other unequivocal test - electron microscopy of the edge. Since not many of us have one of those in the shop, I prefer the scrap of pine.:D

Richard Dooling
06-13-2009, 2:04 PM
Well I will bow to those with more knowledge than me, but I find it very counter intuitive that given one particular piece of metal , with no contaminants (no film), and a properly honed edge that a duller surface can be as sharp or sharper than a mirrored surface.

David Keller NC
06-13-2009, 3:49 PM
Richard - If you look again at what I posted, you will see that I did imply that, all things being equal, (in other words, the same piece of metal and the same stones/paper/compound) one could infer that a more polished result means a surface with fewer (and smaller) imperfections. Though, of course, this does not translate to sharpness exactly - one can have an absolutely mirror finish and a dang dull chisel if the bevel/back are rounded to any degree.

But what you asked in the first post isn't "all things being equal" - I'm inferring that you switched to a different honing compound and found that you were getting a duller-looking surface. Under such circumstances, it's certainly possible that the formulation of the compound results in a low-luster surface finish, despite the resulting scratches being equal to, or smaller than, another stropping compound.

Again, what you want to do is evaluate the cutting action of the tool on the end grain of EWP. If it cuts cleanly, it's way beyond razor sharp, and certainly so sharp that there is no shop operation for which it would be unsuitable.

Wilbur Pan
06-14-2009, 7:42 AM
I have to admit this is taking things a bit far but a mirror surface must be smoother than a dull surface. A dull surface is dull because the light is being scattered by surface irregularities. A shiny surface is shiny because the surface is microscopically so smooth that parallel light rays remain parallel when reflected off the surface.

This is true, but the smoothness of the surface is only one factor in how sharp the edge of a tool will be. Flatness is important, as is the actual size of the surface irregularities.

For example, take a tool and sharpen it on an 8000 grit man made waterstone. Man made waterstones have sharpening particles that are nearly identical in size. This will leave a very even scratch pattern, and have a mirror finish. An 8000 grit waterstone should leave scratches of about 1 micron in size due to the size of the particles, which make this tool really sharp.

Now take the same tool, and sharpen it on a natural waterstone. Natural waterstones will have sharpening particles of various sizes, due to their nature. Suppose your waterstone happens to leave a scratch pattern with a variety of sizes ranging from 0.3 to 1 micron. Because the scratches are of different sizes, the tool will have a duller appearance. But that tool will also be just as sharp, since the largest scratch is 1 micron, same as the result from the 8000 grit man made stone.

The real world example of this is Japanese tools. I don't think anyone will dispute that Japanese planes and chisels can be made extremely sharp. But Japanese tools sharpened with natural Japanese waterstones tend to have a hazy, matte appearance to them, and they can still make thin endgrain shavings with ease.

Finally, a mirror finish is not the same as flat, which is also required for a sharp edge. To prove this, think of a funhouse mirror. It's very shiny, and has a mirror finish, but is certainly not flat.

My main point is that there are many factors that go into determining how sharp a tool edge is, and mirror finish is just one of them, and it seems to me that there's a fair chance that it may not be the most important factor. Having said that, if you are using man made sharpening materials -- sandpaper on glass, or man made waterstones -- a mirror finish is what you would expect as you work your way towards a sharp edge. Just make sure that the reflection isn't distorted as well, which would indicate that the surface isn't flat.

With your original green compound question, my bet is that one brand of your green compound may have a wider range of particle sizes than the other one, which explains the difference in how shiny the tool is. But the maximum size of those particles is still really small, which gives you a very sharp tool after using either one.


Now if I can just get better at establishing a consistent blade camber.:rolleyes:

My method for consistently getting a camber on a blade is to try to make a perfectly straight profile on the edge. I'm guaranteed to get a camber that way. ;)

Tim Put
06-14-2009, 2:09 PM
I tried to make the case that a shiny edge must be sharper months ago. Curiously,some po-poed the concept.To me it seems perfectly logical.

Why don't some of you try stropping with Simichrome,or Flitz as an abrasive?

I can't remember which one at the moment, but one of the ASM handbooks makes very clear that a mirror finish, though somewhat correlated with actual surface quality, is not a good indicator. Matte surfaces can be both flatter and smoother than a mirror surface.

I'll try and find it later, but I don't give myself very good odds of finding it. Each manual is several thousand pages long and there are, what twenty?

Johnny Kleso
06-14-2009, 8:33 PM
Dico is the #1 maker of polishing compounds..
htp://www.dicoproducts.com/ (http://www.dicoproducts.com/)
The LV is very nice to use as it has a very good wax that binds it..

Richard Dooling
06-15-2009, 9:35 AM
Thanks for everyone’s input!

David, I reread my “Well I will bow to those with more knowledge than me . . .” statement and wanted to be sure you didn’t take that wrong. I didn’t mean to come off as being irked or whatever. This,"Matte surfaces can be both flatter and smoother than a mirror surface," just escapes me.:confused:

The important thing here is that I’m finally getting consistently sharp edges that scare the hairs off the back of my hand and cut softwood end grain very cleanly. I was cutting some practice dovetails the other day and realized that I have become more comfortable chopping out waste than sawing it. I’m actually surprised how few mallet blows it takes to chop through a ¾” board if you have a sharp chisel!

One of the great things that has come through practice is that I hardly ever reach for sharpening or honing guides any more. This has really sped up the whole business. I also carved out a small area in my shop to keep my stones and strops always available so it’s very easy to touch up a tool. If I were relying on a guide I wouldn’t be able to do this. I have also stopped using micro bevels because I would have to use a guide.

Modern plane blades are great because their thickness provides a nice big surface to press against the stone. As many others have pointed out, initial grinding on a wheel helps make it easier to keep the edge in proper contact with the stone. Still, some of the thin old Stanley irons keep me reaching for the guide.

Cliff Rohrabacher
06-15-2009, 9:51 AM
I use a 3-M automotive aluminum oxide polishing compound made for black lacquer finishes it comes in a bottle for about $40.00 to get a super mirror finish

I also like this stuff on glass plate:
http://www.diamondtool.com/
http://www.diamondtool.com/dialapng.html

0.5 Micron - gray
1.0 Micron - white
2.0 micron - ivory

But you could use any of the above on wood or leather just fine.

Tony Zaffuto
06-15-2009, 1:36 PM
George,

I have used Simichrome to polish with and the subjective feel of the chisel was not as sharp and not as bright as other methods!

I have some of the LV green compound and although it does a great job, I can get a better (shinier) polish using Dupont Perfect-It III Auto compound. A quart costs about $12.00 and the one I bought five years ago, still is better than 3/4 full. I spread a little on a piece of MDF and strop on that. I get a better edge using this method than with any other compound or diamond paste.

T.Z.

David Keller NC
06-16-2009, 9:56 AM
"The important thing here is that I’m finally getting consistently sharp edges that scare the hairs off the back of my hand and cut softwood end grain very cleanly. I was cutting some practice dovetails the other day and realized that I have become more comfortable chopping out waste than sawing it. I’m actually surprised how few mallet blows it takes to chop through a ¾” board if you have a sharp chisel!"

Richard - no offense taken. What you noted is what is often lost in the raging internet debates over sharpening systems, power sharpening systems, waterstones vs. oilstones vs. diamond plates and whatever else someone dreams up. All of them have advantages and disavantages, and it matters not one whit whichever one you use so long as you can do exactly what you're describing - achieve a sharp edge.

Personally, I'd rather do woodworking than spend hours on "the perfect grind".:D