On Mon, 16 May 2005 11:52:16 -0700, Jake in Escondido
wrote:

I have some nice ceramic tiles that are heavily incrusted with water
deposits (Metal content- calcium). They are vertical and quite a few
square feet and acid washing is not practical. It was recommended that I
sandblast the deposits. I don't want to damage the tile, so I was
wondering what might be the best medium to blast them with. Any ideas or
cautions?

I have a similar problem with unglazed tile. Well, actually it is
patterned and colored concrete that simulates unglazed tile. Acid
washing doesn't differentiate between the unwanted minerals and the
original surface, and neither would blasting.

What I've found that works is a light touch with the most aggressive
nonwoven abrasive wheels from McMaster, and my 4.5" angle grinder.
With the attack angle as low as possible, and the surface dry, it
knocks the minerals loose and only slightly smooths the original
surface - provided you move on once you see the original surface. If
it is too aggressive for some areas, lowering the rotation speed works
much better than moving to a finer grit. Wear dust protection!

Loren