Don,

 

I've bought a number of "antique" sharpening stones, mainly for their
natural shape or the combination of stone and wood they were in.  I also
have a number of stones including the hard black Arkansas and translucent,
probably from Woodcraft, which either came un-flat or later required it.  I
think I have mostly flattened concave surfaces  These and my Japanese
Waterstones are flattened on DMT brand diamond plates.  If you have a
choice, use the coarsest one you have.

 

To be kind to the diamond, I wash the oilstone in detergent and scrub with a
coarse brush.  This is just to get as much of the oil grunge off it.  Then
flatten it dry on the diamond plate.  I let the diamond do the work and
never press down heavily.  When flattening Waterstones, I do it under a
gentle stream of water.  Shortly after starting you will see the areas that
are flat and those that aren't by color.  It is a quick process.  I turn the
stone around often so that I'm not leaning more on one side than another.
This will not damage a quality diamond sharpening plate.  The dust can be
wiped off both the diamond and your stone with a brush, cloth or water.  For
a very fine Black Hard stone such as yours, you will probably want to
lighten up the pressure towards the end or rub it against a much finer
diamond at the end.  You'll be surprised how clelan, quick and easy the
process is.

 

Gary Laroff,

Portland, Oregon 

 

 

> On Apr 8, 2018, at 6:06 PM, Don Schwartz < <mailto:dks@t...>
dks@t...> wrote:

> 

> 

> I have a small Black Hard Arkansas stone which is concave ( hollow Jeff)
on one side and convex on the other. I know the convex side is going to be
hard to flatten, so I'm working on the concave side. I am using a coarse
Norton Crystolon stone  ( SiC, 100 grit maybe ) with my usual mix of lamp
oil and dish detergent ( washing-up soap Jeff). It's cutting, but I'm
finding it very slow going. Apart from a surface grinder, is there a better
way?

> 

Don,

 

I bought a translucent Arkansas stone that the seller said he flattened on a
diamond plate. It is definitely flat. Diamond should cut the black too. 

 

Bill