Sharp tools with matte finishes

[Wilbur Pan]

The issue of whether shiny equals sharp has come up in this forum before. Although oftentimes the advice is given is to use whatever sharpening method you use to achieve a mirror finish, there are two problems with this piece of advice.

First, a sharp edge is achieved by the intersection of two flat surfaces, and flat is not necessarily the same as a mirror finish. If you don't believe this, look at any funhouse mirror, or the parabolic reflector in a flashlight. Those are certainly reflective surfaces that are not flat at all. A mirror finish is a characteristic of how even/repetitive the surface pattern is. You can certainly achieve a flat surface that is reflective, and you can use the reflection to see how flat your surface is by seeing if there is visible distortion in the reflected image in your tool. But the fact is that the flat and mirror finish are not equivalent.

Second, from an observational standpoint, tools sharpened with manmade Japanese waterstones will take on a very reflective surface, but those same tools sharpened with natural Japanese waterstones often can have a hazy or matte surface, even though either method can result in an extremely sharp edge. Here's an example of some chisels sharpened with natural Japanese waterstones, where you can see the matte finish that is left by the waterstone:





I've always felt that one explanation for this phenomenon is that the grit sizes in natural Japanese waterstones had more variation than what is seen in manmade waterstones. This leads to a more random scratch pattern in tools sharpened with natural Japanese waterstones, which diffuses light, which leads to the hazy surface. Manmade waterstones, on the other hand, will leave a more regular scratch pattern, which leads to an increased reflectivity and that mirror finish.

Recently, Ron Hock has posted some electron micrographs of tools sharpened with natural and manmade waterstones that support this theory. The tools sharpened with natural Japanese waterstones have a more random scratch pattern compared to the manmade waterstones. This may not be entirely due to grit size variation. It could also be that the natural Japanese waterstone develops more of a slurry, and that the sharpening particles are moving in a more random manner than the manmade waterstone, where it could be that the majority of sharpening particles are still embedded in the matrix. The shape of the abrasive particles also probably plays a role.

Again, this is not to say that you should aim for either a matte or mirror finish when sharpening. The point is that how reflective the tool surface is not necessarily the same as a flat surface, and flatness is really the goal when sharpening a tool.

[Robert Rozaieski]

I think there's a lot of merit to this explanation Wilbur. I find that with my natural Arkansas stones, the finish is kind of hazy as well, but the tools are plenty sharp. When I used Norton (man made) water stones, I got a mirror polish. Now that I use the natural oil stones, the polish is not a mirror but the edge is just as sharp as when I used the Nortons. The irregular crystalline structure of the natural stones makes sense to cause such an irregular scratch pattern, resulting in the hazy finish.

[Richard Dooling]

Finally an explanation that makes sense. Thanks very much for this post Wilbur.

.

[george wilson]

I don't se what FLAT has to do with MIRROR. A mirror can be in any curvature,but it has nothing to do with flatness. There is flawed logic in this part of your posting. Yes,we want flat surfaces coming together,but they can be flat and polished if we hone them accurately. If I want a
little crown in a smooth plane iron,I can hone that in too,still keeping it polished.

I'll stick with making 2 polished edges come together. A polished edge consists of a more finely divided surface than a matte finish does. Flat,or slightly curved,the edge is sharper.

This looks like the beginning of another long,pointless thread about sharpening. The work I posted here was all done with polished edges. This is something that professional woodworkers would laugh about. I have been a paid,professional woodworker for 48 years,and worked wood for 8 years before getting paid to do it. That makes 56 years. Just get some work done.

Your larger chisel looks like the edge has indentations,and a broken off corner. If I wanted to post an edge I made,I wouldn't post a flawed one.

[David Gendron]

Sorry George, but I think you should read the post again. You would see that what Wilbur is saying is actualy that a mirror/polished surface doesn't meen it is flat!! And also, all respect to your great woodworking skills, Japanese have been using edge tools for quite a wile and done prety amazing stuff with them, with out a polished or mirror finishe on the face of there tools. Just thinking of those shaving contest!!
Wilbur, this is of great help, I also think that you don't need mirror to achive great Sharpness!

[harry strasil]

I remember my father telling me about my Grandfather delegating my dad during his apprenticeship to forge the sockets of chisels that were worn down to nubs like the ones shown into tangs and rounding the cutting edges so the sawmill loggers could finish using them as Barking Spuds.

[george wilson]

Of course mirrors are not necessarily flat!!!!! So what does that prove? Stropping will make edges more rounded. Just don't strop TOO much. Look at any razor blade including new ones. They are stropped. A mirror edge is smoother than a matte edge.Two mirrors coming together will be sharpest. Of course,it is possible to DUB OVER an over stropped edge. That's why I don't use powered strops. It takes SKILL to make the sharpest edge.

A basic problem with this subject is that everyone has their own idea what a truly sharp edge is.

David,I want you to take a straight razor and sharpen it with a matte finish,and try shaving your face with it. No stropping(like has been done FOREVER by barbers). Maybe that will convince you which edge is sharpest.

How many of you have shaved with a straight razor? I have. And,I certainly put a stropped mirror edge on it. Whiskers are thick and tough. You might get by shaving arm hair with a matte finish,but you won't like the way a razor less than dead sharp pulls out your whiskers instead of smoothly shaving them.

It's just common sense.

[Ben Rivenbark]

I shave with a straight razor every time I shave. Have done so for years. I hone my own razors, and have people who regularly call me and ask me to hone their razors for them.

Normally, I strop before every shave. It keeps the edge going longer, and *does* make the edge smoother - typically. But, if you've ever used a good quality Nakayama finishing stone from Japan, you'll find that you don't need to strop your razor right after it comes off the stone, provided you have honed it well enough. Japanese naturals do make for a very smooth finish. A straight razor with a matte finish can be a killer shaver.

Please get a high power microscope and hone two straight razors properly; one with a high quality japanese natural and the other with whatever method you prefer. When comparing stone to stone under the scope, the japanese natural will provide a much finer scratch pattern than most any other stone available.

Stropping with Chromium Oxide or similar will give a fantastic scratch pattern as well, but the shave is merely equal, not necessarily better.

You can get a mirrored edge with lots of stones, and 99% of them will be lousy compared to the finish shown on the chisel above.

I actually have a video of myself shaving with an old hickory paring knife that I honed to 6000 grit, with no stropping, and it shaved fantastically. It's on youtube under the channel Ben325e, if you like.

I will concur that non-power stropping is one of the easiest and fastest ways to get a fantastic edge on most anything. Chromium oxide on newspaper taped to a granite reference plate is REALLY tough to beat. An excellent quality Japanese natural finisher will cost hundreds of dollars; a lifetime supply of chromium oxide will cost about fifteen bucks.

[Tim Put]

A mirror edge is smoother than a matte edge.
...
It's just common sense.

In this case, as in many others, common sense is wrong. Shining like a mirror only shows that a significant proportion of the surface is very smooth, not that all of it is. There can be completely invisible, very large (relatively speaking), very significant defects on a mirrored surface that will be the dominant effects on sharpness. As can be seen in the SEM images posted by Hock, and linked to by Wilbur, the scale of the surface features causing matte or shiny appearance is much smaller than the scale of the edge defects limiting sharpness.

Summarized, it may be possible for a perfect shiny edge to be sharper than a matte edge, but a matte edge can be as sharp as you or anyone else has ever made. Matte-ness is not a limiting factor.

Further, a matte surface may in fact be smoother than a mirrored surface for reasons having to do with what causes a surface to act mirror-like in the first place; but the point above is sufficient.

[george wilson]

A lot of sharpening is skill. You should strop in different directions to keep smooth mountains from building up. Technique MUST be considered,not just what you use to get a tool sharp. It also depends upon what wood you are working. Aren't Japanese tools designed primarily for soft wood use? I never liked Japanese type tools,so never use them.

[Wilbur Pan]

I don't se what FLAT has to do with MIRROR.

What you are describing as "polished" I am describing as the "mirror finish". And if you had read the first sentence of the second paragraph in my post, you would see that we are in agreement on this point.

Again, if you read my original post, I am not saying that a chisel with a polished bevel cannot be sharp.

Of course mirrors are not necessarily flat!!!!! So what does that prove?

David,I want you to take a straight razor and sharpen it with a matte finish,and try shaving your face with it. No stropping(like has been done FOREVER by barbers). Maybe that will convince you which edge is sharpest.

How many of you have shaved with a straight razor? I have. And,I certainly put a stropped mirror edge on it. Whiskers are thick and tough. You might get by shaving arm hair with a matte finish,but you won't like the way a razor less than dead sharp pulls out your whiskers instead of smoothly shaving them.

It's just common sense.

It may be common sense, but there's nothing like experience to see whether an assertion holds up. Here's an end grain shaving I made in pine with a Japanese chisel with a matte finish left by sharpening it on a natural Japanese waterstone, along with a plane shaving I made with a Japanese plane, also with a matte finish from a natural Japanese waterstone.



I'd say that's pretty good evidence of tools with a matte finish and how sharp they can be.

By the way, I can put a polished surface on this chisel and plane blade with a manmade waterstone, and get a similar shaving. That should show that the polished vs. matte finish really doesn't come into play in determining how sharp a tool edge is.

What does matter in sharpness is how deep the scratch patterns are when you're done with the sharpening method of your choice. If you have scratches that are, say, 1 micron deep when you're done, and those scratches are arranged in a very regular fashion, you'll have a sharp tool with a polished finish. If your sharpening method leaves you with scratches that range from 0.5 to 1 micron deep that are more random in arrangement, that will leave you with an equally sharp edge that has a matte finish.

As far as straight razors go, if you look at the straight razor forums, you'll find people who use a strop to sharpen. You'll also find people who use Japanese waterstones. The people who sharpen their straight razors with Japanese waterstones report that they get a matte finish on their razors, and they are perfectly sharp.

One last thought about "common sense". There's a great quote that's often attributed to the famous philosopher Yogi Berra, but probably belongs to Jan L. A. van de Snepscheut instead. It goes, "In theory there's no difference between theory and practice. In practice, there is."

[Wilbur Pan]

Aren't Japanese tools designed primarily for soft wood use? I never liked Japanese type tools,so never use them.

That is not correct, either. I use Japanese chisels, planes, and saws in a variety of North American hardwoods. For an example of how a Japanese chisel can hold up against cocobolo and white oak, see here.

[Eric Hartunian]

That is not correct, either. I use Japanese chisels, planes, and saws in a variety of North American hardwoods. For an example of how a Japanese chisel can hold up against cocobolo and white oak, see here.

Wilbur, I remember this post and the consternation it caused!
I think we are all in violent agreement on this issue, just stating it differently.
I use both J tools and western, and I fully agree that shiny isn't necessarily sharp, and matte finished isn't necessarily dull.
George brings up an excellent point, however. No matter how fine your natural waterstone is, or how fine the rouge on your favorite strop is, poor technique will never deliver a sharp edge. When I started using mostly hand tools, I had some very shiny edges that would not pare end grain or anything else, but boy, were they shiny!
I like to sharpen. It is part of the craft and I enjoy it, so these discussions are interesting to me. However, I recognize that the point is rather academic. George's polished edge is sharp; Wilbur's matte edge is sharp; they both will do the job.
If this discussion pops up on the JT forum, I would be interested in what those comments will be.

Eric

[george wilson]

I really don't care how you want to sharpen your tools. I know what works for me. This discussion has been made before,so we just disagree.

[Wilbur Pan]

Just to be clear, I don't think there is anything to disagree about. I agree with you that a polished tool can be quite sharp. I've done that with my tools as well.

Where we seem to diverge in outlook is that you seem not to believe that a tool with a matte finish can also be quite sharp, regardless of evidence to the contrary.

This isn't a matter of disagreeing about an opinion, however. Many people have very sharp tools and razors that have a matte finish. This is a demonstrable fact.

I'm not asking you to change your methods of work. What I'm asking you to do is realize that oftentimes there are multiple means to the same end.