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This is an interesting approach
Japanese Woodworking Forums :: View topic - Grit Tests on Natural Stones and Shapton
...just thought i would bring it to your attention. Maybe someone wants to help Alex out per his request, or share thoughts or photos. here or there I'll read it.
Now I want a nakyama even more!
Amazing pictures, Tim zowada has some similar pictures at his website.You can see some hefty scratchmarks from the shapton 30k there to.:shrug:
Hey Kris that site is a place where you can catch up on japanese stone information. There isn't tons and tons of info, but there just isnt tons and tons of info anywhere on the web.
TEST#1
Please take a look at the third picture (30K Shapton). Pay special attention to the scratches on the unhoned body of the blade.
Now look at the 4th picture (Nakayama 1). It's obviously the same part of the blade same magnification, so the unhoned scratches on the body should appear exactly the same.
They do not. Someone is trying to favor the Nakayama. It does only take a minor adjustment of the lighting angle, to make a dramatic difference.
http://straightrazorpalace.com/advan...ent-light.html
I own a Nakayama myself, and I find it an excellent hone.
I don't own a Shapton, but I'm sure, based upon many testimonies of guys I trust, that it's an excellent hone as well.
I love science and scientific methods, even conducted by non-scientists with crude setups. But I hate it when bias is disguised as science.
On the same note, honing is about sharpening, not about scratching. How fine a hone polishes is only one factor contributing to its sharpening capabilities.
Bart.
Good observation Bart. The edge improved dramatically again by just by adding the ruler in the pic. ;)
The other big problem is that at 25x those pictures aren't really even showing the results of the shapton or nakayama no matter what the lighting happens to be. They're showing the results of the hone that the bevel was set with. It takes an awful lot of honing with a nakayama or 30k shapton to hone down past grooves of those sizes.
In the Verhoeven paper he shows 3000x electron microscope photos of edges honed on a variety of stones and pastes, and the grooves from the 0.5 micron chrome oxide are surprisingly small even at that magnification. The Shapton hone that this Japanese site is talking uses abrasive granules about that same size.
Hi Bart. If i get what it is you are looking at, there is not an unhoned part of the blade. What you are seeing is the weld line between the hard steel and ironQuote:
Originally Posted by Bart
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. "Quote:
Originally Posted by mparker762
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.
Note that the picture with the ruler looks much different than the picture above it. Evidently the position of something varies from picture to picture.
Ah. This is only my opinion/impression from looking at the pictures and reading the text. The photo with the ruler is not meant as part of the continuum, only provided for a better sense of scale. The relative comparison is the progression from 12k to nakayama.Quote:
Originally Posted by Quick
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 ? :shrug:
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 likeQuote:
Originally Posted by JimmyHAD
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. :D
it's not a debate of pressure / no pressure:jedi:
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.
Not if you're just interested in shaving.Quote:
Originally Posted by JimmyHAD
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.
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.Quote:
Originally Posted by kevint
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?
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.Quote:
Originally Posted by kevint
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.
Thank you for your reply Bart.
What I was referring to by animosity was the sudden turn to accusation of bias, fraud, ignorance. This in spite of the fact the description of the method specifically mentions the aspects of lighting and limitations of the equipment. Ignorant statements about how the appearance of scratches can be manipulated to appear smooth or deeply furrowed, combined with assurance that these cannot be 30k because they are too coarse in appearance is far less than I expect from an intelligent conversation.
This kind of response, and I have seen it before. Along with the mindless buddy system of thanking up the rep, like some middle school popularity contest truly makes me question my participation here.
I just want to check something ... you guys do realise that his image size is one centimetre NOT one millimetre don't you?
He mislabelled it in at least one place:
http://www.g-ray.co.uk/pictures/scale.JPG
yes. As I've stated several times in this thread, those photos don't demonstrate what that poster claims they demonstrate.Quote:
Originally Posted by Rajagra
Quote:
Originally Posted by kevint
His photos do not demonstrate what he claims they demonstrate. To see submicron features requires a microscope capable of a very high magnification. There have been multiple papers published (Verhoeven's Knife Sharpening Experiments 2002 paper, and the Popular Mechanics article from the 20's) that show these scratches accurately, and both of these used 3000x magnification. Verhoeven used an electron microscope, and the PM article used a custom-built optical microscope.
The 25x magnification the linked poster used is simply inadequate by roughly two orders of magnitude. It is not ignorance nor mindlessness to point this out, nor is it ignorance nor a matter of popularity to note that this means that the linked poster is either unaware that he needs a much bigger scope or he is intentionally trying to deceive the readers. And it seems reasonable to point out that one factor that makes the ignorance option more likely (or at least more understandable) is the possibility that confirmation bias may have played a part. And it is not unintelligent to note that the sorts of effects that the photos do show are the sort that have tripped up previous attempts to analyse hone scratches with low-power microscopes. Nor is it out of line to describe how small differences in lighting can have a huge effect on the sorts of surface features that show up in the photos.
It is possible that the OP of the linked thread is absolutely correct in his conclusion that the Nakayama hone is markedly superior to the Shapton 30k. I've got both and think they're roughly equivalent, but it's possible that I'm wrong. But this conclusion is not bolstered by the photos in that linked article. I'm sorry to disappoint you, but the resolution is just too low. Even at 3000x the scratches are surprisingly small, and at 3000x you can look at the blade edge-on and measure the width of the cutting edge to the hundredth of a micron, and at that magnification the scratches are roughly the same size as the ones shown in the 30k shapton photo. So if the guy in the linked thread is right about those scratches, then somebody needs to tell Prof John Verhoeven at the University of Iowa that he needs to learn how to use an electron microscope. Or maybe, just maybe, it's the random internet poster with the 25x microscope that's wrong.
Maybe.
right. as labeled: 1/2 mm scale. I may have read over a typo, but I thought it said. 1cm was enlarged to to fit 25cm screen which equaled an approximate 25X magnification.Quote:
Originally Posted by Rajagra
Yes, each division on that ruler is 0.5mm, total widtch about 1cm. Where he says "Width of Sample Equals 1mm" it is wrong.Quote:
Originally Posted by kevint
I only mention it because I've been trying to take some pictures through a microscope and it's difficult. My jaw dropped when I saw the quality of his pictures until I realised they weren't really micrographs at all.
Here are my first feeble attempts, scale roughly 1mm top to bottom,
Unbranded Double Arrow as bought, Dovo honed by me (after shaving, unstropped), Wapi bought shave-ready (used & stropped.):
http://www.g-ray.co.uk/pictures/Double%20Arrow.JPGhttp://www.g-ray.co.uk/pictures/Dovo.JPGhttp://www.g-ray.co.uk/pictures/Wapi.JPG
Mr. Parker. I considered the tone of replies to be quite negative. Your text overall; contradictory.Quote:
Originally Posted by mparker762
Please, I fouind Mr. Parker's tone very much in line with yours to which I think he was responding. I found the content to be interesting, informative, and in my opinion, quite valid.Quote:
Originally Posted by kevint
"This kind of response, and I have seen it before. Along with the mindless buddy system of thanking up the rep, like some middle school popularity contest truly makes me question my participation here."
So far the discussion has been directly to the topic. The analysis of the study, done by someone else, which you presented. I think it's fascinating, pertinent, and very worth dissecting. There's nothing wrong with attacking the data and/or methods used to reach a conclusion. I do not mean this to be inflammatory, but what did you find contradictory about Mr. Parker's text? If it was content, then please elaborate. If it was tone, then hopefully we can just let it drop.
(Don't let this valuable thread die over this.)
Finally found the Verhoeven paper, which should help correct the overemotional rhetoric and ad-hominem attacks in this thread.
Experiments on Knife Sharpening
September 2004
Prof. John Verhoeven
Emeritus Professor
Department of Materials Science and Engineering
Iowa State University
Experiments on Knife Sharpening
On page 19, figure 23, he shows a blade sharpened on a 6000 grit waterstone, at 3000x and 800x resolutions. Notice how small the grooves are, even at 800x magnification.
On page 30, figure 37, he shows a blade with a secondary bevel formed on chrome oxide. He doesn't give the grit, but he does describe it as the standard chrome oxide block sold in woodworking stores for honing chisels. At best this is the 0.5 micron Lee Valley block, at worst it's the coarse stuff that's blended with other abrasives. If it's the 0.5 micron chrome oxide then the grit is comparable to the grit of a 30k Shapton (my Shapton is 0.48 micron). Even at 3000x, the grooves in the secondary bevel are very thin and very shallow, and are therefore unlikely to be visible at 25x as the author of that linked article claims. Admittedly I'm comparing a 0.5 micron paste to a 0.5 micron stone, but Verhoeven shows an awful lot of photos of 1k, 6k, and 8k honing marks at a variety of resolutions, and the marks from even these relatively coarse hones are surprisingly small.
I do not apologize for being negative about the linked post, nor for being contradictory about his assertions. But if Prof. Verhoeven's pictures are accurate depictions of micron and submicron-scale honing marks, then it is clear that the centimeter-scale photos in the linked thread must be showing much larger honing marks and not the 0.5 micron - 0.2 micron striations that the Shapton and Nakayama hones would be producing.
I hope I haven't soured you on the Verhoeven paper, but it is well worth reading front to back. He shows comparative micrographs of commercial Gillette razor blades and a straight razor that was honed by somebody that used it, and the straight razor comes off looking quite well. And the photos are quite eye-popping.
One other issue with that guy's honing is that he is simply polishing the bevel, not getting the egde any sharper!
Check it out. The bevel is certainly seeing what seems to be improvement, but the dark line along the edge remains untouched.
Good example of what happens if you do not "set your bevel" and move up the progression anyhow. You get nice shiny bevels, and a razor that still won't cut right...
http://thejapanblade.com/images/heal.jpg
Not really sure what we're looking at there. Is it all bevel? with a hard/soft steel boundary or bevel and blade.
In any event, in the part that is blade or soft steel there are large discolorations/bumps/pits or whatever they are. There are two especially large ones close together almost dead center in the pictures. If you use one or more of those marks for reference it seems that the scratches above and below the marks are erased in the progression of pics but but the mark remains virtually uneffected. Would those be tiny pits in the metal?
buddy system ?.... like some middle school popularity contest ?
It’s all over the forum… but I honestly thought I was the only one to notice.
My comments have been strictly about content, gentlemen. There is nothing against the man in what i have said. I have respect for everyone that has posted here. ive read your posts;) I was full of slurry there for a few minutes, I feel well lapped now:)
Contradictions are not hard to come by when honing. If you don't see it, my pointing any out will add no clarity to the subject.
First let's remember that is not a razor bevel. I believe you can tell nothing about the edge condition in these pictures. they are for scratch comparison.
what you are seeing if it is not clear is described in the article. It is a forge weld of hard high carbon steel edge to thicker backing of wrought iron.... We know that a 30k ceramic stone will polish to a high mirror and it will leave very small scratches. You can guess this even if all you have is an 8k
you can see the difference of the kasumi finish of the natural stone very clearly with the naked eye. the naked eye appearance of each type is perfectly aligned with the side lit magnified photos.
The reason one is shiny and the other matte, is the difference in the scratch pattern. They are radically different. There are two things that may explain the dichotomy. Both related to binder as Bart mentioned. The nat binder is weak allowing clumps of particles to be released and easily break down. The synthetic may be releasing clumps of particles; however, the binder "might be" keeping those small particles acting as single larger particles.
some could be pits, but I don't feel like looking again:) Quick. I believe you are seeing inclusions, often silica which is considered a desirable condition in the iron.Quote:
Originally Posted by Quick
I have read the paper and discussed it here several times.Quote:
Originally Posted by mparker762