I have ceramic tile on a cement slab foundation. Some of the tiles have become loose and I have removed them. I want to reinstall the tiles, but there is mastic stuck to the back of the tile. Any idea how to remove this without cracking the tiles? I have 8-10 tiles to reinstall. Thanks!

Well, here I go again. Check out the Fein Multimaster at Fein Power Tools USA Quality Precision Power Tools (http://www.feinus.com). The videos are convincing. Warning, it's pricey. There are two scraper blades available, one is hard and the other flexible. It removes material by oscillating up to 20,0000 osc/min. It will work for you.

Ptandatx - What I have used several times is a propane toruch and a wide putty knife, I would run the flame over the back side to heat the addhesive and take the putty knife and easly scrape across the piece of tile. I found that is a lot safer then anything else. I hope I have helped you with your problem, If I have rate my answer below ::: Good luck & GOD BLESS ::: F.B.E.