closing the grain

["George Graham" <georgergraham@xxxxxxxxxxx>]

To all my polishing friends,

Here is my 2 cents on polishing , closing up the stone, using chemicals and
abrasives.

To polish any stone you must sand down the surface with some kind of
abrasive. It could be any kind of sandpaper. It can be plain woodworking
sandpaper, all the way up to the latest diamond pads. The only difference is
the old stuff does not last very long, but is a lot cheaper! As long as you
go from a course grit up to a very fine grit,(600) you will get a surface
that is ready to be polished.

Some stone cannot be closed up as it has pits and voids . If you are really
fanatical about getting a "perfect" polish you can fill the voids with an
epoxy and then rehone it again. I personaly don't see the need to fill
voids. Its part of the natural stone. If a stone is honed right, then it
will shine. I like to use wet or dry silicone carbide sand paper. Its cheap,
easy to get, and will cut everything from soapstone to basalt. If you want
to sand down to a 3000 grit, and see into the stone, you can. The technology
is available.

After you've sanded until you have got it all out of your system, you have
to make some interesting choices.
It seems like the softer the stone, the more options you have.

You can use oil, waxes, and sealers on soapstones, alabasters and
softlimestone. On the harder limestones and marbles, anything with calcium
carbonate in it, there is a huge varity of lotions and potions, creams and
sealers, and last and not lest, all the stuff that has oxolic acid in it.

What I've learned is that the acid chrystalizes the surface. That is where
you get that wonderful glass finish!

I've done a lot of polishing of granite, and the hard stones will show every
flaw and imperfection in your honing skills, when you polish.

I like to mix some water into tinoxide,then using a hard felt buffing wheel,
thats been saturated with water, start buffing. I don't need high rpm's ,
but the grinder must have a lot of power so I can really lean on it. I need
to generate a lot of heat and pressure to get a shine. I also work as large
an area as possible, so as to not burn and discolor a small area. As the
polish comes up I get lighter with the pressure , I'm always aware that you
can ruin granite with heat, and doing this will get the stone hot. The water
will be steaming off the stone as you work. Doing this will chrystalize the
surface and looks great.

Most of the compounds I've used are white, which really brings out all the
pits and grain lines in the stone. You can tint the tinoxide or oxolic acid
with lampblack when your working on black and gray stones. Masons use a red
coloring agent to tint their mortar. It works great of tinting your compound
red or pink when your finishing a red or brown granite. All this does is
keep any compound residue left in the stone from being noticable. It does
not color the stone itself.

The tips I'm passing on are not easy and you will need to practice on some
scrap. The heat from buffing can really ruin a stone. I never run the wheel
dry. the tinoxide water mix gives you some steady water to the stone, but
the wheel throws the water off as you work. I keep a bucket of water handy
to resoak the entire felt wheel regularly.

If your polishing a curved sufrace of granite you will heat it up quickly,
so watch out for burning the stone. Granite will loose its color , whiten up
and the surface will actually buckel and raise. Then its time to get
creative. Can we all say , recarve, after you have gathered up all the tools
you have thrown about the shop.

I hope this doesen't scare you off from trying to polish granite, because it
can be done, and it is a spectacular material when done right.

Books have been written on this subject, so I'll stop for now.
Good luck, and wear a good dust mask
George Graham