Polishing basalt, granite

["George Graham" <georgergraham@xxxxxxxxxxx>]

Randy,

I haven't used the resin viper pads, but have used silicone carbide discs to
hone granite. I suspect that the common problems I've encountered are
similar to what you are running into.

Polishing black granite and basalt will show any flaws and mistakes in your
work. The common mistakes made are being to heavy handed . When you get to
the finest grits, use a  light touch. Use a lot of water so your pads keep
clean, and slow down your rpms. I've used silicone carbide wheels on an air
grinder that only goes about 1700 rpms. When I get thru 320 grit I take the
wheel off the grinder and rub the areas by hand to even out the finish. Then
I finish with a 600 grit silicone carbide disc. I can't stress enough how
even and light you have to be when you are at that stage. If your grinder
has the slightest wobble in it, then when the pad hits the stone its leaves
the streak. Slowing down the rpms may help a lot.

I've done all my polishing with tin oxide powder, on a hard felt pad that
was slightly damp. Tin oxide is very white, so the old solution to white
pores in colored granite was cured a couple of ways. The rule of thumb is to
add red coloring powder ( that is use to tint concrete and mortar,) to the
tin oxide for all the pink , brown and red granites. I used lamp black to
darken the tin oxide when I was working with all the black and gray granite.

What I call India black, is really not a true granite . I've read that its
basalt. Anyway it doesn't polish up as quick and a true granite, so I leave
the tin oxide pure for the polishing and then go over the whole thing with
pure lamp black to stain any of the polishing compound black, that's left in
any pores.Very messy!

The better the the honing job you do , the less pores are a problem.
I've found that black granite  and basalt are the most demanding. The small
scuffs and imperfections that are almost invisible on gray and colored
granites will stand out like a sore thumb. Polishing black will force you to
do your best work.

One note of caution. If you work the stone in a small area and it gets to
hot, it will turn white. The only fix is to quit for the day, go to your
favorite tavern , and drown your sorrows away!

Be patient, and good luck.
George Graham