Some techniques for painting ceramic tile include using a special primer such as XIM 400 that’s designed to bond with ceramic tile. It’s also possible to sand ceramic tile or rough its surface with a muriatic-acid-based deglosser before painting it with bonding primer and latex wall paint or a two-part epoxy paint.
One strategy for painting ceramic tiles is to prep and bond the tile surface and then to spray it with an acrylic coating that hardens into a stone-like finish that covers grout lines. Although you can do this yourself with proper training, often it’s less expensive to paint over ceramic tile with special paints and bonding agents.
To prepare ceramic tile for painting, first clean the tile, removing any soap deposits, mold and mildew. Wait for the area to dry completely before choosing between sanding with 180 to 220 grit synthetic grit sandpaper such as silicon carbide or aluminum oxide or using a deglosser such as XIM's muriatic-acid-based products. If you choose to sand, use an orbital sander to save time. If using a deglosser, work with good ventilation. Wipe the deglossed tiles down again, and allow them to dry before painting.
Prime the tiles with an epoxy or urethane bonding primer, and then paint with semi-gloss or high-gloss latex paint. This process gives you the best combination of sealant and color. To save a step, you can also use two-part epoxy paint. This eliminates the need for a special primer, but your choice of colors is limited.