Thread: shoubudani asagi kan

Originally Posted by SharpMan

How do you flatten your natural stones, those that are very hard? I read some
can kill a diamond plate even. I tried flattening one with sic paper, but noticed
the some of the sick grit that came loose from the paper would get stuck in the natural stone. I could see little black dots in my natural stone.

Sharpman

So you're sure the black dots aren't part of the stone ? If you look under magnification some stones have brownish or blackish dots on them called "goma" they aid cutting strength. If the dots you see are raised & shiny you have SiC particles embedded. I actually like to use SiC powders but mostly for heavy work. On wet float glass they would be the fastest most aggressive way to flatten a natural stone that I have tried. If needed you can remove a lot of stone with 40 - 80 grit & save your diamond plates. I have not experienced any particles embedding in jnats but heavy pressure may be the culprit if you do. I use various diamond plates for lapping after that as it is less messy but SiC cuts fast. Softer powders like AlOx or automotive valve grinding pastes, which are usually a mix of the 2, will work but even the SiC breaks down quickly. The slurry you build needs to be wiped off if stiction becomes a problem or sometimes adding water helps but as I said it is messy.

Originally Posted by onimaru55

So you're sure the black dots aren't part of the stone ? If you look under magnification some stones have brownish or blackish dots on them called "goma" they aid cutting strength. If the dots you see are raised & shiny you have SiC particles embedded. I actually like to use SiC powders but mostly for heavy work. On wet float glass they would be the fastest most aggressive way to flatten a natural stone that I have tried. If needed you can remove a lot of stone with 40 - 80 grit & save your diamond plates. I have not experienced any particles embedding in jnats but heavy pressure may be the culprit if you do. I use various diamond plates for lapping after that as it is less messy but SiC cuts fast. Softer powders like AlOx or automotive valve grinding pastes, which are usually a mix of the 2, will work but even the SiC breaks down quickly. The slurry you build needs to be wiped off if stiction becomes a problem or sometimes adding water helps but as I said it is messy.

Thanks for the informative post. Yes the dots(4-5) were raised. Not sure if they were shiny.
I do think I used more force than necessary. Than I used a crappy diamond plate
to flatten more and the dots disappeared after 15-30 minutes.

I was thinking of using the AlOx to flatten the stone and at the end just use
a diamond plate so if there was any embedding the diamond plate would remove it,
make sense?I guess having a very hard stone would reduce the risk
of embedding in the stone. You think pure aluox could embed in a very hard stone?
I was thinking sic is much harder than alox, so perhaps sic or even grit that is softer
would be a better idea. Of course it would probably take longer with the softer grit.

What do you think of the idea of using 30.000grit sic or alox powder on a jnat?
check this:
YouTube - ‪knife sharpening using Maruka finishing stone with SiC slurry ( #30,000 green carborumdum)‬‏