toolman946 via CraftKB.com wrote:
I have a black, hard Arkansas oil stone that's probably close to 100 years
old (handed down from grandpa). The surface isn't flat anymore and it has
some chips and dings from many years of service. It doesn't seem to cut very
well too, and I'm guessing the pores are filled with dirt and dross. I've
read about techniques to clean the surface (such as a good long soak in an
oil dissolving cleaner and baking in a stove) and I had been planning to go
at the surface with a diamond grit flat stone of similar width. Has anyone
had any experience (good or bad) with rejuvenating an old timer like this?
Sure. Oil well, and rub on a carborundum stone that is
relatively flat. I think the carborundum stone will wear down a
lot quicker than the Arkansas. I have lapped a bunch of bench
stones of various types back to flatness this way. You have to
watch the shape of the stones, and flip end to end frequently,
and due to the difference in hardness you may still end up with
a curvature. By controlling the pressure at the ends or center,
you can somewhat control where the stones are wearing down. The
idea is to use a LOT of oil, so the stones are not grating
against each other, but an abrasive-loaded oil film is doing
most of the work.

Jon