grit size, lapping stones, and the finish they provide

Perhaps you have some experience with leather stropping. If so, you know that it is possible to drag a sharp edge across the surface of a piece of bare cowhide and see an increase in shininess. No abrasives, raw cowhide. What causes this? Is it smaller scratches? No, it isn't scratches at all. The leather can't cut the steel because it isn't hard enough to cut it. What causes it is burnishing. The steel is actually pushed into a shinier state rather than being cut into a shinier state. If you have ever seen a cabinet scraper, their edges aren't caused by grinding or abrasives at all. They are pushed into shape by rubbing them against another piece of steel.
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Stropping leather has a natural abrasive in it that WILL cut steel and that is why bare leather polishes steel.


You continue to argue that it is burnishing, how do you explain the picture above of the much finer scratch pattern? If burnishing does not remove steel then why did it come off on my stone?

Burnishing wood http://en.wikipedia.org/wiki/Burnish

Burnishing metal http://en.wikipedia.org/wiki/Burnishing_(metalworking)
 
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Thanks for links to definitions of burninshing but I'm already familiar with the term. No, leather won't cut steel unless there is an abrasive embedded in it. It is too soft. I didn't say burnishing doesn't remove steel. What I said was that it is a process of pressure or pushing rather than cutting. The steel on your stone was caused by cutting. I said your lapped stone works primarily from burnishing, not completely from burnishing. Obviously it did some cutting and I said so in my post. But the cutting isn't what polished it. Burnishing polished it. In order to polish it by cutting you would need smaller abrasive particles. It can't be any other way. It's impossible to cut your way to a shinier finish without smaller grits. It is easy to burnish your way to a shinier finish. It takes very little to do that as I have explained earlier.

Again, I'm not fighting your observations. I'm fighting your explanation of how they occur. Give me some arguments based on science and physics. Then you can change my mind. Logical arguments work really well with me. Arguing against what I didn't say doesn't do it for me at all.
 
I never set out to tell anyone how it works but for what ever reason it does, Spyderco found this out long before us.

There is a natural occurring abrasive that is in leather, it is brought out when the leather is compressed and that is why quality strop leather is pre-compressed. There's more too it than just compression but that's one of the big parts.

Diamond stones on ceramic is not burnishing its cutting, The only reason the diamond stone wear out is because of the matrix they are held in place by. I'm sure that the pressure of the two stones touching is more than enough along with things like harmonic vibration and all the ceramic floating in the slury to aid in the destruction of the diamond stone. While I would at a guess say that if you could see what each diamond was doing to the ceramic surface at a very magnified level it would probably look like a axe being dragged through the dirt. You are creating a scratch pattern in the surface of the ceramic with the very tips of the diamond sticking out of the matrix, kinda the same reason you get a finer finish on steel by using less pressure with diamond hones.
 
No, diamond stones just wear down. Simple as that. Because the abrasive particles are fixed and permanent, they simply wear with use. As that happens they cut more slowly as anyone who has used one can tell you. It is not dissimilar to what you do when you lap an abrasive. The reason stones with a soluble matrix cut so quickly is that the worn particles are constantly replaced by fresh ones.

Try some finishing waterstones (grit size 5000 or smaller.) You will find that they are very efficient at producing polished edges. They do it by cutting primarily and burnishing only secondarily. They work very quickly.
 
Knifenut, I may have figured out where our confusion lies. If an abrasive particle has been lapped then the scratches it delivers to the steel will be shallower because the particles are "duller" or, better, worn. That would result in a "smoother" looking finish on the blade. Grinding is nothing more than applying scratches to the steel, after all. A smaller grit will produce smaller scratches. A smoother abrasive will produce shallower scratches. They aren't the same thing, of course, but they can both have a similar effect visually. Perhaps that's where our differing explanations can meet.
 
Sometimes some stones work better on carbon, some stainless, and some stones leave a different surface texture when used for polishing different steels
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Glad I'm not alone in my theories.


I don't think there is a confusion but I do think you have a lot to learn about how a diamond stone works. Call DMT, its what I did.

No, diamond stones just wear down. Simple as that. Because the abrasive particles are fixed and permanent, they simply wear with use.
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Not that simple.

The steel on your stone was caused by cutting. I said your lapped stone works primarily from burnishing, not completely from burnishing. Obviously it did some cutting and I said so in my post. But the cutting isn't what polished it. Burnishing polished it. In order to polish it by cutting you would need smaller abrasive particles. It can't be any other way. It's impossible to cut your way to a shinier finish without smaller grits
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I don't let it get to the point of burnishing because I don't want plastic deformation or metal being placed back on the edge from a loaded stone.

The results from my UF stone are the results of abrasion, its very obvious from the picture as you can see all the fine scratches. Burnishing would not produce the almost burr free hair splitting edge that was on that knife or the scratch pattern for that matter.

I have let the stone load to the point of burnishing so I do know what it is like, its a down grading effect and is very obvious.

By cutting a ceramic stone with a diamond you are fracturing the ceramic particles causing them to become smaller. Similar to what happens with sandpaper after repeated use.
 
Hi - I just came across this forum and noticed that more than a few have somewhat of a dilemma with grit size. This is just a way that I have solved this problem for me for what it's worth. It may not work for everyone, okay.

I can see where some have pointed out the problem with trying to get the info from manufactures. I have never had any luck with this also. Most just know the 'average' size and little other info. And I have not found a supplier rep that will understand that the maximum grit size of a product can have more meaning than the average size.

So, when I wish to know just what I have, I take a very small amount and put on a glass slide, cover it with clear tape and put some other abrasive of known size next to it and cover it. If it is in powder form, just this. If it is in a liquid vehicle I will again take a small amount and wash the liquid out with a solvent such as alcohol or acetone and then with the dry grit again put on a slide and just look at it with a microscope. This will give me a relative size. And for determining just how this will act on a material surface, polish a sample and look at it with a magnaviewer of choice.

I realize that there are unlimited other ways of doing things but this is just one way that I have found that works for me.
 
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