Porcelain is a hard, nonporous material that comes in many colours, making it a useful choice for sinks. Although a porcelain sink adds beauty to your bathroom, it also can be chipped or cracked if hard objects are dropped on it. A crack is not permanent, however; it can be repaired.
Wash the sink using a nonabrasive cleanser or mild soap. Rub a soft cloth over the cleanser to remove any residue on the sink. Rinse the sink and let it dry thoroughly.
Sand the cracked area with medium-grit sandpaper until the damaged spot is smooth. Sand only the area that is cracked so you don't scratch the surrounding porcelain.
Wipe the sanding debris off with a cotton swab dampened with rubbing alcohol. Dry the area completely with a soft cloth.
Mix the epoxy repair solution, following the package directions. Fill the crack in your porcelain sink using a toothpick or small brush, based on the size of the crack.
Let the epoxy solution dry for at least 24 hours. Do not use the sink while the solution is drying.
Remove any excess dried epoxy with a razor blade so the sink's surface is uniform.
Apply a high-gloss, alkyd-based paint matching your sink colour to the area you repaired. Let the paint dry for 48 hours before using the sink.
Keep the location of the crack or chip dry. If the crack stays wet, the repair is not likely to hold up.