Lately I’ve been playing around with other ways to make use of my micro-photo setup besides just taking pictures of the edges of kanna, and one thought that came to mind was to see how different sharpening stones look under high magnification.
All the photos below are uncropped and taken with the same setup, approximately producing images that you’d see looking through a 400x microscope. With an optical microscope setup like I’m using, quality lighting is a big challenge, especially on the finer grit stones. The course stones are much more legible simply due to the larger particles, while things become more uniform and less detailed on the finer stones. Nonetheless I think it’s still pretty interesting to visually see the changes in grit size and density, through the progression of stones.
First up is a “fine” grit Kensho brand diamond stone. This is a lightly used stone that has only been used for lapping my water stones. This stone is composed of finely spaced diamond clusters embedded in a steel sheet.
The sandy white-ish color grit you can see here is residue from lapping my sharpening stones. In an effort to get a clearer view I scrubbed the diamond stone with a brush to try and clean it up a bit.
Here’s the same stone, but a different set of diamond clusters after a bit of cleaning and washing.
And another view of the same stone. This time showing more of the transition between one cluster and the surrounding space.
For one more diamond stone comparison, here is a shot of my 400 grit Atoma diamond plate. This is a heavily used stone that I’ve been using regularly for at least a year. The Atoma is also only used for lapping my water stones. Despite being much more heavily used than the previously shown Kensho diamond plate, the Atoma looks pretty similar, and actually appears to have more diamonds still intact.
Next up are some shots of synthetic water stones, starting with a 700 grit Bester.
1000 grit Naniwa Hibiki
6000 grit Naniwa resin bonded diamond stone
8000 grit Kitayama stone
12000 grit Naniwa Kagiyaki. The black streaks here are residue from sharpening a kanna. This is the only stone which I didn’t lap and clean prior to shooting.
There’s definitely a lot of room for improvement with these shots, particularly when it comes to lighting, and I hope to update this series of posts as I improve the process.
I used to teach microscopy and microsope illustration. Lighting is a huge issue with microphotography and I think you are on the right track because these look great. I’ve never seen pix like these before.
One thing I might suggest for comparison illustrations, is to either include a reference scale in the photograph or added later in processing. The reason is that, “400x” is nearly impossible for folks like me to grasp, but “Here is something that is 0.1 mm” is much easier to visualize.
It can be a simple ruler in mm or 64ths or a digitized scale, or some other object whose size is recognizable.
Also, I don’t know your set up but if you could pull it of pic of the stone and the resulting kanna blade sharpened on it at the same scale would be fantastic. I don’t think I’ve ever seen something like that before.
Easy for me to say since I don’t have to do the work!
Gary, Thank you!
Your recommendation to include reference scales in the images is a great one, and something I ignored when first posting these photos. I’ve updated most of the images now to include a scale.
Really interesting that you used to teach microscopy. I may have to pick your brain sometime. All of this is pretty new to me, but thanks to a pretty amazing online community of folks who have shared their techniques and process, I’ve managed to get myself this far.
Different comparisons such as what you mentioned, contrasting a sharpened blade shown at magnification alongside the respective stone is something that I’ve been thinking about a lot lately. I’ve tried to do that to a certain extend in a recent post and video showing the sharpening process along with high magnification shots of the blade after each stone. So many possibilities, it all just takes a bit of time.
Hi, thanks for your blog, the research and knowledge shared.
You are using an Atoma 400 diamong plate for lapping your stones. I was wondering if the grit of your lapping stone has an effect on the stone you use and on the sharpening results. one could think that a 400 grit stone will leave it’s “400 print” on your finer stones and that it could be “transfered” to your tool. I was wondering that because some use another stone of the same grit to lap stone to prevent that but I was wondering if it has really an effect. Any clue?
Thanks again
Hi Anthony,
The short answer to your question is that no I haven’t seen any ill effects from using a 400 grit Atoma on my finish stones.
I have heard people talk about using a fine lapping plate for fine stones, but I’ve also never seen any actual evidence showing one way being better than the other. Instead it’s usually just anecdotal.
My impression of that argument is that a course lapping plate will leave deep scratches, with peaks and valleys, on the surface of the stone. But it’s unclear to me what the negative effects of that will be. Does that mean that the peaks will cut into the edge of your blade more, producing a jagged edge?
My guess is that even if a 400 grit lapping plate leaves deep scratches in a finish stone, the stone is still far softer than the steel in your blade, and in no time you are going to wear through the peaks and the surface is going to even out.
I have experimented a bit using finer diamond lapping plates on my finish stones as well as using GC nagura stones, and in neither situation did I notice any tangible difference in the quality of the final edge.
All of this is to say that my approach to sharpening is very much geared towards practical, regular work, and someone attempting kezurou-kai level sub-10 micron shavings may have a different opinion. But that said, I’ve done a fair bit of kezurou-kai practice for fun with friends, and we’ve been able to easily achieve 10-15 micron thick shavings with the techniques I’ve described here on the blog (going thinner starts to get really tricky, and involves lots of other factors like the moisture content of the wood you’re planing, kanna tuning, etc.)
It would be great if Tod over at the Science of Sharp blog ever evaluates these kinds of questions with his SEM microscope to get some visual evidence.
Best,
Jon