Ceramic tile over sealed concrete

I am installing ceramic tile in a basement over an old concrete floor that had been painted about 20 years ago. I have removed the paint by mechanical scraping and sanding. The concrete floor has a very smooth finish and water beads on the bare concrete, so I am guessing that it had been sealed.

What additional work must be done to prepare the floor for the tile mortar?

You can try a little paint stripper in a corner, but I don't think it will do a lot. I would buy the highest rated super dooper flex thinset they make and go from there. TEC makes a good one, and so does Custom Building Products. This stuff will cost $25 to $30 per 50 lb. sack, but they say it will stick to glass. And I think it will.

Maybe we'll get a second opinion here.

John Bridge
http://www.johnbridge.com