Making the Chinese 12k perform faster and finer (my secret)

[cotdt]

I've gone through about 5 different samples of Chinese 12k, some are finer than others but for the most part, they are pretty consistent.

The way the stone is typically used is with clean water. This is the wrong way, as the stone would have very little abrasive power and is rather scratchy. I get a similar finish to my Naniwa 5k with very light pressure, more like a Naniwa 3k if I use a little pressure. This is too coarse for razors, and very slow.

A much better way is to get a DMT XXC and create THICK slurry with it. Notice that now the Chinese 12k cuts MUCH faster and is just as fine as with clean water. As you keep going, the slurry particles break down until you finally get an ultrafine, milky finish similar to Japanese naturals. It can bring out the hamon in some of my Japanese cutlery.

Keep the slurry thick and use light pressure!

You end up with a finer edge than the typical way of using this stone, while cutting much faster. This same technique also applies to those hard blue Nakayama stones.

[cotdt]

I forget to mention, the shave is very good straight off the stone! But even better if stropped.

With knives it's amazing to see the white slurry you make quickly turn dark with swarf, and realize that you are using the "slow-cutting" Chinese 12k.

[Kingfish]

I would never have thought of using such an aggressive DMT xxc for raising a slurry at that end of honing. Have you tried higher grits first and then concluded the xxc was the right tool to get the most out of that hard stone? I gave up on the c12k long ago with so many better stones out there, but I will have to try your method and clean the dust off my most unused stone. I promise not to tell anyone your secret.
Mike

[cotdt]

I would never have thought of using such an aggressive DMT xxc for raising a slurry at that end of honing. Have you tried higher grits first and then concluded the xxc was the right tool to get the most out of that hard stone? I gave up on the c12k long ago with so many better stones out there, but I will have to try your method and clean the dust off my most unused stone. I promise not to tell anyone your secret.
Mike

The finer DMT stones tend to get stuck via striction and not be able to generate much slurry. Surface prep does make a difference but in this case during use the rougher surface refines itself and the slurry breaks down. I save my slurry by just letting it dry, so on the next use I have something that is already fine. I use low pressure as this stone's surface is scratchy.

Let us know your results if you try it! This secret method doesn't make this the best stone in the world (my Japanese naturals are better) but does make the Chinese 12k a very usable stone that can both cut and finish.

[holli4pirating]

I'm confused... Are you saying your C12k's give a finish similar to a Naniwa 5k? That was not my experience at all. I agree that the C12k is a slow cutter, but mine is extremely smooth - not scratchy at all.

The bit about the slurry is interesting - I never bothered to play much with slurry on my C12k. I did notice, however, that lapping with a DMTC left scratches in my C12k, so I would worry about deeper scratches from a DMTXXC, but I guess you got good results so it's no problem.

[Piet]

I think your secret should stay a secret because it makes no sense.

Could it be that because you scratched it with your DMT it acts like a coarser stone? Adding thick slurry would fill the scratches and make it smoother.

What you should try is lap your Guangxi all the way to 1200-1500 grit sanding paper and use it with clean water. I have a feeling that if you're patient enough you will be impressed.

[mainaman]

Can you tell us how did you determine that the grit breaks down with the use? Were you able to visually compare scratch patterns with time or did you use other methods?

[northpaw]

The way the stone is typically used is with clean water. This is the wrong way, as the stone would have very little abrasive power and is rather scratchy. I get a similar finish to my Naniwa 5k with very light pressure, more like a Naniwa 3k if I use a little pressure. This is too coarse for razors, and very slow.

I'm interested in your method, but the above statement seems kind of odd.

After lapping my own C12k up to P-2000 paper, it's like honing on glass. I understand the "little abrasive power" part, since it really just polishes, but I don't see how anyone could possibly think it was scratchy. You could probably drag your eyeball across it a time or two without much damage. (kidding)

As a previous poster mentioned, have you tried lapping one to a super smooth finish and compared the edges it yields (100-200 strokes) with the ones you get with your method?

[zib]

I use a DMT XXC for cleaning up stones after they've been cut. It makes fast work of it. Stones look like they've been dragged over concrete after you take a XXC to them. I don't know that I hone off it. Why not just use a slurry stone? You can have a smooth surface and a slurry...Also, I've read this before, and I'm confused. How do you lapp a stone into a different grit. If it's 12k, and you raise a slurry, isn't the slurry 12k too?
Isn't it just cutting faster?

[rodb]

I forget to mention, the shave is very good straight off the stone! But even better if stropped.

With knives it's amazing to see the white slurry you make quickly turn dark with swarf, and realize that you are using the "slow-cutting" Chinese 12k.

I tried this with a DMT C as I don't have a XXC.
I took a razor that very reluctantly would pop arm hairs and did 50 laps on the C12k with heavy slurry, then 20 on a green Chromium paddle then 70 on leather. Now it pops arm hair almost silently!!

I haven't shave test this yet, but this seems to work pretty well with my C12k. Through magnification the razor almost has a mirror finish on the edge.