said by sempergoofy:I'm thinking you might have to find a way to put pressure on your tiles on the ceiling until the thinset hardens so that gravity does not pull the tile away. Must be a way to solve that if it is, in fact, an issue. It may just stick and work.
Supposedly it'll just stick. I believe it, given the stickyiess of the thinset I'm using. Still, I've got visions of 18" tiles falling onto my head during installation.
One internet guy says to backbutter the tiles and use the zigzag side of the trowel to make circular marks on the tile like a bullseye. Supposedly that makes the thinset act like a suction cup and hold the tile up better while the mortar cures.