I got a primer called "Grabber" at Home Depot. The sales person said it would cover the tile in my bathroom but cautioned to allow for long drying time. He said the primer should dry for at least 24 hours then put on a semi-gloss or other high gloss exterior paint and let that dry for at least 24 hours. I've only applied the primer...it adhered to the tile well. I'm hoping that this will work well enough to paint the bathtub and tiles on the floor.