If you have a ceramic toilet with a crack forming, you'll need to fill and patch the crack before it worsens. The best time to do this is when you first notice the crack appearing. If the crack is left to widen, it may cause the toilet actually to crumble into large pieces, spilling the water in the tank and bowl over the bathroom floor. Patch your ceramic toilet with a few materials in about an hour.
Put on rubber gloves and clean the ceramic toilet with ammonia wipes. Allow the ammonia to evaporate from the surface before continuing.
Spread ceramic epoxy over the crack on the toilet with a plastic putty knife. Smooth the epoxy with the blade of the plastic putty knife, scraping away excess. Let the epoxy to dry for 6 to 8 hours or as long as directed by the manufacturer.
Abrade the patch on your ceramic toilet with fine-grit sandpaper to make it more smooth and to blend with the surface. Wipe it down with a tack cloth thereafter.
Clean the patch with acetone and cotton balls. Wait about 10 minutes for the acetone to evaporate completely.
Treat the patch with ceramic refinishing spray, applying a light coat. Wait 24 hours for the spray to dry.