I'm getting ready to put a ceramic floor in the basement bathroom (2 year old home). I understand that it's OK to put the tile on the concrete but about a year ago I painted on the behr's basement sealer to reduce the concrete dust.
Can I apply the thin-set on top of the sealer or do I need to prep this floor with something else first?
You're not gonna get as good a bond as you need most likely? Test the slab for porosity by placing several drops of water in various spots. The water should soak in within 10-15 minutes. If possible compare with untreated areas.
If that is inconclusive, bond several small samples to the floor using a good grade modified thinset mortar. Try to remove using lateral force after 7-10 days.
TILE GUY - retired- TROY, MI - Method & Product suitability consulting.