Rotten stone is a natural mineral used for polishing.
Its finer in texture than pumice or diatomaceous earth.

Rotten stone has been used for fine polishing of brass and varnished
surfaces for ages. Its usually available in paint stores (right next to
the packages of various grades of pumice) and if its a really good
paint/hardware store you might find "tripoli" compound for polishing
stainless steel, etc..

To use: Flat sand the surface with increasingly finer and finer grades
of wet and dry sandpaper (ending with 2000 grit); then for a satin
finish use a very clean felt pad with a little bit of oil and
sprinkled with rotten stone and rub lightly along the direction of the
grain until the surface becomes warm. The heat of friction will also
develop an irridescent glowing 'patina' in the wood cells. For an
ultra gloss surface as above but using water instead of oil. Best is
to simply use a clean bare hand with a few drops of water and rotten
stone. If you ever have seen the ultra gloss finishes found on mega
yachts, private jets or museums .... this is how they get such
finishes. Obviously the varnish must be completely cured before
hand-rubbing/polishing. For varnish application just build up many thin
layers of varnish and allow to cure throughly before polishing. The
frictional heat from the hand polishing will make the varnish look like
glass and the wood cells underneath the varnish will absolutely GLOW.
There are other surface finishes that are more brilliant (french
polishing using shellac, etc.) but are vulnerable to water.
Do a websearch for "rotten stone" polish.

This is essentially the same technique used for finalizing lacquer
finishes on the most expensive automobiles and pianos, etc. .

In article .com, Lyn
& Tony wrote:

I notice the use of "rotten stone". What is it.
Great articles. Will try some of the tips.
Tony
S/V Ambrosia