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

Originally Posted by danielghofrani

sure but for the folks who DO use the diamond plates: why don't you use the finer ones? DMT makes 8k level diamond plate

Probably it sticks way too much, also there are better options for 8k lvl stone than DMT, buying one for making slurry is probably waste of money.

Originally Posted by alx

I am looking for 2 straight razor users to come to Sonoma for a honing session to act as independent participants. I believe that I can prove that the grit from Japanese tennen toishi is as fine or finer than a Shapton 30k stone.
I will provide a 600x microscope for all of us to use, I have a Shapton 30k on glass stone, of course a few stones to play with, and lunch.

It would be helpful is one of the users has a video camera, HD prefered and knows how to use it, and a seperate Shapton 30k. If those fellows or gals who can come do not have either of those items, maybe they can borrow, beg or steal the items.
Professional sharpeners welcome as well as observers. I have a dedicate shop.

In the past a few of you have been to my shop and you know I love to sharpen for hours and hours and hours. So those who can come be prepared to spend the better part of a day here.

Because I am self employed almost any day of the week will work although Sundays - Thursdays are best.
No reason not to communicate through this thread. best wishes, Alex

Did you find 2 candidates for this honing session?
I was reading that not to many razors can take the edge from sharpton 30k, any experienced with that?
perhaps its different with j-nats to get to the 30k range but nevertheless the article im talking about claims that
many razors collapsed meaning the edge off the sharpton 30k.

Originally Posted by danielghofrani

sure but for the folks who DO use the diamond plates: why don't you use the finer ones? DMT makes 8k level diamond plate

8k diamond plate on a stone is like impossible to move the plate on there its gets welded on there!

Originally Posted by danielghofrani

sure but for the folks who DO use the diamond plates: why don't you use the finer ones? DMT makes 8k level diamond plate

I don't use DMT's as they stick to the stone but I do use the finest Atoma plate ie 1200 grit. The pimpled surface prevents sticking.

When lapping a stone, the 600grit does not remove particles in the size of 600 grit, or even 2k grit. Lapping is not like woodcarving with a chisel that removes big pieces of wood. Stone for our case. You can use 30 grit sandpaper, and what you see is powder from a stone, fine powder for the fine stones. DMT says that if you use its finer diamond plates for lapping, they get worn out pretty quickly, especially in the presence of slurry, and those diamond-nickel(?) particles are also released from the diamond plate with the slurry of the stone.
Basically, many hones, especially the hard ones take forever to produce slurry from rubbing them with a hard nagura but with a diamond plate it's very easy. I don't usually prefer diamond plates for producing slurry, but how I think it works.

There are some excellent close up photos of DMT & Atoma diamond plates on the Jende Industries Blog, a wealth of information.

DMT vs. Atoma Diamond Plates For the Edge Pro – A Microscopic Comparison « Jende Industries Blog

My normal formula for honing razors when I test a stone is to create a fresh bevel with 45degree scratches from a 5k Suehiro stone, and to then proceed to remove those 5k scratches with straight on slightly angled scratches made with the stone being tested. I always do this testing with a slurry made from the base stone using a diamond plate. This way the whole process is done 100% with the grit of the base stone being tested. The addition of grit from a Aichi or tomonagura would give me a false +/- result. I always sharpen with a slurry made with a DN (diamond nagura), it is quick, easy, foolproof and does not in itself interject rogue grit. Diamond plates are more popular in Japan than they are here, if you go to the shows everyone uses diamond plates. Atoma is a very popular brand and they can be refurbished by yourself by ordering a new layer of the nickel sheet that has the diamonds imbedded. This is self adheasive so the milled aluminum plate does not need to be discarded.

Here are some photos taken with an SEM microscope for a fellow I met in Japan, his name is Lovic and his blogs are very interesting.

鋸-鉋-鑿　（Nokogiri-Kanna-Nomi）: June 2008

No one ever did respond to my offer to come over and use my shop. I finally ended up with a method of using awasedo slurry dust on a plate made of "plate glass" and found that the japanese grit particles began to break up immediately and get smaller. The blades became more and more polished. The grit particles eventually just turned into dust and were too small to continue honing or refining the blade. And in fact I could never get the kiita slurry to polish the blade like the Shapton 30k did. Funny how a blade less shiny can shave just as well and even more comfortable with less razor burn. Alx

What is this Taiwanese black stone and where can I find it?

Grit is all important to the honing/sharpening process. Honing is a progressive process going from coarse to fine to finish. The manufacturers of artificial hones go to great lengths to make sure their finest grits are within specified ranges which is why the finer the grit stone, the more expensive it is (in general). If coarser grits are mixed in with finer grits then the published grit of the stone would be the coarsest grit as that's what will show up on the bevel as deeper or finer scratches. To answer you question though about Japanese Natural stones, there is a mystique to the Japanese stones which many folks buy into and justify all kinds of prices in the purchase thereof. I've a number of Japanese stones in my collection and some are of very high quality and some . . . not so much. By "not so much" I mean the stone's hardness varies across the surface with hard and soft spots, fissures and/or cracks, the thickness of the stone is different from one end of the stone to the other, the backside of the stone often isn't finished and looks like it was hacked out of the parent stone with a chisel making the backside unusable, etc. The high quality ones are very nice with none of the above problems but there are lots of stones out there which will do just as good a job at honing and cost a lot less.

Originally Posted by alx

Funny how a blade less shiny can shave just as well and even more comfortable with less razor burn. Alx

While I am no expert at this, I wonder if the polish of the bevel has much to do with the sharpness/smoothness of the edge. I had a near wedge razor that was honed with no tape and the bevel was wide and absolutely mirror, but shave was only mediocre. I had a razor honed by Stefan whose bevel had a sandblasted look under the loupe (finished on jnat BTW) but extremely sharp and smooth.

Originally Posted by Howard

the backside of the stone often isn't finished and looks like it was hacked out of the parent stone with a chisel making the backside unusable, etc.

If the stones were inexpensive these points can be valid,however,the reverse can be true also. High quality stones are often left with unfinished backs as the skin helps identify the mine.
Shallow decorative chiselling, not hacking is also sometimes done on favoured & high class stones.