Thread: What is Grit in Japanese Natural Stones, and How Important Is It.

I do like the idea of checking the edge with under a microscope, but, I'm not sure if you will need a 400x or more microscope. Steel has its limits, and you can see them at 50x. With 2000 magnification, if you look straight at the edge, it looks flat, not sharp, no matter the abrasive material you use. For broken glass, you might be able to see for edge a line of single molecules, but for steel, that's as fine as it can get...

I am game, but need a game plan. Alx

Originally Posted by Vasilis

I do like the idea of checking the edge with under a microscope, but, I'm not sure if you will need a 400x or more microscope. Steel has its limits, and you can see them at 50x. With 2000 magnification, if you look straight at the edge, it looks flat, not sharp, no matter the abrasive material you use. For broken glass, you might be able to see for edge a line of single molecules, but for steel, that's as fine as it can get...

50x is the most magnification needed to show all the significant detail of a razors edge? really? then why do all these pics at at even higher magnification seem to be grossly lacking in detail? the resolving power of the microscope or the focal range?
WONDER PHOTOS REVEAL UNSUSPECTED FACTS ABOUT Razor Blades and Shaving (Oct, 1931)
maybe you are thinking of the above article? i dont think 50x shows the detail of the steel to its limit.
http://www.scribd.com/doc/79125884/K...arpening-Study
i think this may explain why you find 50x sufficient, but why i dont think it is.

No, I wasn't thinking a specific article. But i will read those. I am sure that at 2000x magnification we will see many more details, and they do look really cool. But this 50x, it's enough to show us if it's sharp enough for shaving. and the scratch pattern of the hones. As I said on my last post, and looking the pictures of the article, the edge of the sharpest razor under a 2000x magnification looks like half melted cheese. And the surface you see is just the 1/10000th of the whole length of the razor. to check the rest of the edge, it will take you hours. Of course, the higher the magnification, the more details you are able to see, but for the purpose of finding a very very fine hone, and checking the edge, with a 50x we will see enough details.

Stefan, thanks for your responses, I pretty much agree with everything you said. Alx

Originally Posted by SharpMan

Ok things just got more difficult. Which pictures are you referring to
when you said the scratch pattern from a coticule is much finer than
that of a shapton 30K?

I was under the impression that CrOx 0.5 micron was the same size
as the 30k Shapton particles.Vasilis where do you read that the scratches
left are 0.49 micron?

Sharpman

Regarding this post, I don't remember where I read about the 0.49 micron scratches, but I do remember that it was a reliable person and kind of makes sense. Looking at the photos of scratches from a coticule and this 30k shapton, it doesn't really looks like its somewhere near 30k. Most of the people who have one say that they are excellent for shaving, so I don't know what's going on. And, yes, the CrOx 0.5 micron and the 0.49 micron particles of the Shapton should leave comparable edges. I would like to know your opinion, if you have one Shapton 30k how fine is it compared to the CrOx.

I may be an idiot for thinking this, but if Japan and Oregon were joined at one time wouldn't it have the same basic geology?
Has anyone ever checked out the rock from Oregon? Is that to far fetched?

The original photos I took for my website about 5 years ago were not very good quality and they were in my opinion flawed in that the scratch patterns photographed on the blades were made with a slurried stone. All the stones I tested including the Shapton stones had a slurry generated with the same diamomd plate. I now think that the granuals in the slurry reflected the grit of the diamond plate rather than the stones intrinsic grit particle size. The same is true I believe of the actual surface of the diamond conditioned stone itself, there must be grooves left on the stone that more represent the diamond plates action rather than the stones intrinsic grit.

It is for this reason that the popular polishing techniques of the razor hone users here are encouraged to "polish their stones" to a mirror like shine that reflects a perfect image when held at a low angle. When a high quality tennen toishi is polished with a tomo or hon nagura the surface will become smoother without a doubt, and a harder stone will achieve a higher polish by definition. If a stone has a high polish working surface, this granular polish will effect the steel being applied in a likewise hard polished manner, simple physics.

Likewise if that same stone has a rough surface, the roughness will more agressively abrade the steel.

As I believe Stefan suggests and it is a good one, any tests would benifit by the: any slurry made up using a hon-nagura (a portion of the base stone). And I feel that any tests done without a slurry should be done with polished host stones Natural or Synthetic, with equally prepared surfaces. Alx

Originally Posted by Vasilis

Regarding this post, I don't remember where I read about the 0.49 micron scratches, but I do remember that it was a reliable person and kind of makes sense. Looking at the photos of scratches from a coticule and this 30k shapton, it doesn't really looks like its somewhere near 30k. Most of the people who have one say that they are excellent for shaving, so I don't know what's going on. And, yes, the CrOx 0.5 micron and the 0.49 micron particles of the Shapton should leave comparable edges. I would like to know your opinion, if you have one Shapton 30k how fine is it compared to the CrOx.

Originally Posted by Wintchase

I may be an idiot for thinking this, but if Japan and Oregon were joined at one time wouldn't it have the same basic geology?
Has anyone ever checked out the rock from Oregon? Is that to far fetched?

Correct me if I'm wrong, but I believe that the origins of these fantastic Japanese stones was a volcanic event, so it would depend on whether the event occurred while the two landmasses were still joined or not. I'm thinking that this occurred after they already separated.

Given that though, Oregon does have some volcanic activity, so it's possible that at some point in the past a volcano in Oregon threw up some similar materials, and they just need to be found and mined...

Anyone from Oregon want to start searching?

The world is full of hones. The Japanese ones are just the most famous. And, it's not just volcanic activity. Under there, there should be the correct conditions, temperatures, pressure, for the rocks to become hones, and must find them the right moment, when they have the best characteristics. In 100000 years from now if humankind still exists, they might be able to use the sand of Sahara to strop their razors. And this sand, I don't know, 1mil years ago? could have been rocks, and those rocks might have been excellent sharpening stones. In the history of earth, hones come and go. Today's cheap slate tiles, in 5000 years might become the finest hone ever existed, and our descendants (is this the right word?) might pay in their currency, 1000$ for a 5x2" piece.