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've read that baking soda is used for sensitive areas. Not sure how
it'd work for your use. Otherwise, walnut or plastic beads might do the
trick.