Thread: experiments

I'm certainly not an expert but FWIW, having been around about a year and having read a lot of threads, I don't even worry about removing scratch patterns completely from one hone to another. Taking what I interpret to be Lynn's lead "less strokes are better".

Maybe I am misunderstanding it but how many hundreds of strokes would I have to do to get a totally smooth edge leaving only 30K scratches ? When the TPT tells me it is sharp enough and the hairs on my leg pop effortlessly I test shave and pay no mind to the state of the scratch pattern. Am I in error here ?

Originally Posted by JimmyHAD

I'm certainly not an expert but FWIW, having been around about a year and having read a lot of threads, I don't even worry about removing scratch patterns completely from one hone to another. Taking what I interpret to be Lynn's lead "less strokes are better".

Maybe I am misunderstanding it but how many hundreds of strokes would I have to do to get a totally smooth edge leaving only 30K scratches ? When the TPT tells me it is sharp enough and the hairs on my leg pop effortlessly I test shave and pay no mind to the state of the scratch pattern. Am I in error here ?

I think you are missing the point. It isn't an article on how to sharpen. It's only some pictures that demonstrate a method to determine the equivalent grit size of a given natural stone. So I thought for those who like to look, similar comparisons could be done at home. Coticule is 8000? you can test on any steel piece you'd like

Both Mr. Parker and JimmyHAD questioned the time / strokes required. enlarging the photos of the second link in the post, i can read... it calculates to 80 lineal inches of stone by my reckoning.

it's not a debate of pressure / no pressure

You're correct. It is a comparison of the grit size and the resulting depth of the scratch pattern. He is implying "how smooth of a surface/edge can you get with the compared stones". He uses pictures of the scratch patterns to come to a conclusion. What Bart is pointing out is that the pictures are not valid for comparison. The unhoned surface in the pictures appears completely different in the two pictures used to compare the honed surfaces.

Quick,
In what ways they look different to you?

I have tried and posted scratch pattern comparisons in the past but usually some body pipes up that the light is not consistent and it is a fair thing to say. You can bias photography to make the edge look rough or smooth but I don't think this is the case here. I don't really see why anyone would want to publish biased photography on forums. Members tend to know which hone is best and they don't need photography or peer pressure to know which one gives the smoothest sharpest edge. Your face tells you.

When I do it, I try and display in my photography the best image I can get. But light will reflect differently off different surfaces even with constant lighting and it makes it easy to criticise the photography. I can criticise my own very easily.

But using a 200x magnification my observations of what I see with my eyes are:

My Escher ( blue/green) and a natural Suita Japanese hones are both above the 10,000 grit level and they remove grit patterns and leave a matt finish to the bevel rather than a mirror finish that I get with a coticule or chromium oxide. The suita in particular leaves a matt finish. The coticule leaves a clear scratch pattern and shiny mirror finish and the chromium removes the scratch pattern and leaves a shiny mirror surface. Stropping on leather tends to put a mirror finish.

So different naturals leave different finishes.

What I actually look at now days is the edge not the scratch pattern or shiny or matt finish. The crisper/more linear the edge, the sharper the razor.

Once you get above 10,000 grit, I doubt that your face can feel any difference in smoothness.

The edges on the photo's shown above are just fantastic. Tells me the hones are really good. You can not fudge the quality of those edges with lighting.

Originally Posted by JimmyHAD

I'm certainly not an expert but FWIW, having been around about a year and having read a lot of threads, I don't even worry about removing scratch patterns completely from one hone to another. Taking what I interpret to be Lynn's lead "less strokes are better".

Maybe I am misunderstanding it but how many hundreds of strokes would I have to do to get a totally smooth edge leaving only 30K scratches ? When the TPT tells me it is sharp enough and the hairs on my leg pop effortlessly I test shave and pay no mind to the state of the scratch pattern. Am I in error here ?

Not if you're just interested in shaving.

But if you're interested in comparing scratch marks from various hones then it helps to make sure that you've got the light consistent across shots. And it helps to use a high resolution microscope. And it helps to make sure that the scale of the scratches you're seeing correspond to the expected scale of the abrasives you claim to be testing. None of which seem to have been done here. A human hair is roughly 120 microns across, which would mean that the scratches from a 30k Shapton would be at most 1/250th that width (in practice they'll probably be even smaller, because the abrasive grain doesn't seem likely to cut to full depth unless you're using some pressure). So unless the ruler in the original photo is micron scale, those scratches are more likely from a hone somewhere in the 1000 grit range.

Now I would expect that the Nakayama would change the appearance of the bevel, both with the naked eye and under the scope. For one thing the Nakayama creates a slurry of clay and abrasives, which means that the abrasives will create a different scratch pattern that will change the reflectivity characteristics of the blade. For example simply leaving a more matte finish will obscure the scratches because the matte finish scatters the light more, which reduces the contrast. And my Nakayama does leave a more matte finish than my 30k Shapton. Also, the slurry will slosh through those large scratches and abrade their inside surface enough to change the reflectivity there as well, not just the high points on the bevel, while the Shapton, which doesn't form a slurry that I've ever noticed, only touches the high points at the tops of the grooves.

Personally I think the Nakayama and 30k Shapton achieve fairly similar edges. But I don't think these photos even begin to show what the OP in the linked thread claims they do.

BTW it appears that the OP in the linked thread has changed his photos and gotten rid of the incriminating ruler shot, though the new photos still have the other problems.

Originally Posted by kevint

per Mr. AG. quote: "What I am photographing is the light reflecting off of the peaks with the contrast of the shadows in the valleys. "

So you can't really make an assessment of the size of the scratches. I am sure that just as he skews the blade when on the Nat stone to reveal a different pattern, there was a similar effort to be sure that only 30k scratches are left behind.

I'm quite sure he didn't. You can easily get two photos that are similar to the two he showed, without ever touching the blade to a hone, just by changing the angle that the light is striking the blade. I know it's hard to believe, but it's true. At one angle the blade will look like a mirror, at another like black ice, and at another it will look like it's been honed with a chainsaw.

Anyone that has spent much time looking at blades under a microscope has encountered this phenomenon, and will immediately recognize that those photos suffer from the same lighting problems.

It's possible the OP in that thread doesn't realize his mistake - it may be completely inadvertent. And since it confirms his biases he didn't think very hard about what he was seeing. But it is a serious mistake that invalidates his argument. Those scratches in the 30k Shapton photo are not 1/2 micron wide - not at the claimed 25x magnification, and for that matter not even at 250x magnification. Those are the scratches left over from the hone that he used to form the bevel, which was probably something in the 800-1000x range.

I own both a Maruka Nakayama and a 30k Shapton, and have looked at both under a 250x scope, and even at that magnification I can't see the individual scratches they leave; the best I can see are the gradually growing matte (nakayama)/shiny(shapton) areas as I hone, where they are slowly wearing past the scratch marks from the coarser stones. But the slightest difference in lighting can make you think you're seeing a huge change.

In my experience the two hones leave similar edges, though one reason they look different under a scope is because the nakayama's slurry leaves a more matte finish, which reduces the contrast under the scope and makes the residual scratches look less defined and less visible.

You both are basing your opinion on what you think you see, rather than trusting his honesty? Even though he tells exactly what and how and why he did, (such as maintaing the position of the lighting)you both know better because of the photo, is that correct?

Why the animosity?

Originally Posted by kevint

You both are basing your opinion on what you think you see, rather than trusting his honesty? Even though he tells exactly what and how and why he did, (such as maintaing the position of the lighting)you both know better because of the photo, is that correct?

Why the animosity?

I stand corrected about what I first thought was an unhoned and a honed part. I see now, that it's all honed, only different steel.

But I still agree with Mparker and others. It remains extremely difficult to compare scratch patterns by taking magnified pictures. I have taken that route myself, and came to the conclusion that it's an unreliable method to compare different types of hones.

I can adjust a microscope in such way, that it will favour certain types of scratches as very smooth and other types as very coarse, without any re-adjusting in between shooting the pictures. Then, I can make one single adjustment, that will reverse the results if I reshoot the pictures at that point.

For comparing scratches of hones that come of the same quarry, this is less an advantage, but to compare synthetic hones to naturals, I don't accept this a good method.
I would have less objections against SEM-pictures, where an electron stream scans the surface in very controlled conditions, with high resolution and magnification. But even then, what does it matter?

At this level, the edge is as much shaped by plastic flow and debris deposit than by abrasion only. I believe the binder of a hone plays an important role in that. Without owning any, I'm still pretty sure that a Shapton 30K produces a keener edge than a Shapton 16K, that by itself produces a keener edge than a Shapton 8K. Where I have to situate my Nakayama, that I do own, in that list, remains to be seen.
Another, way more important, property of a particular hone, for our purposes, is the capability to produce an edge that skips skin and cuts whiskers. So far, for my skin and whiskers, I have not find anything that can beat a good old Coticule as a finishing hone. At the same time, I need a synthetic hone to push my edges to my desired keenness, before I can finish it on a Coticule or the Nakayama. I can also consider it finished, right of that synthetic, but those edges like to slice my hair papilae as much as my whiskers. Not a thousand magnified pictures can provide me with that information.

But I have no animus against Japanese Naturals, if that eases your mind. In fact I like them.

Best regards,
Bart.