Although porcelain, which is made by fusing metal and glass together, is durable, it is possible to crack. Rather than pay a professional to repair your porcelain sink or replace it completely, stop by your local home repair centre or hardware store for some supplies and try to repair it yourself. Repairing cracks in porcelain is no easy task -- it requires meticulous attention to detail and the ability to work quickly and with precision.
Clean the entire sink thoroughly. Allow the sink to dry completely before starting any additional work.
Sand down the area directly around the crack with a medium-grain sandpaper. Pour a small amount of isopropyl alcohol onto a clean cloth and use it to wipe up the dust and grit. Allow the sink to dry.
Create a solution using small amounts of the alkyd-based paint and the porcelain repair compound. Use a paint that matches the finish on your sink. Follow the directions on the compound's packaging for the appropriate amounts to use based on the size of the crack in your sink.
Dip the tip of a single-edge razor blade into the mixture and slowly fill in the crack. Use enough of the mixture to overfill the crack so it overlaps the edges. If the crack is especially thin, use a toothpick to spread the mixture. Dip one end of a cotton swab in the nail polish remover. Use the cotton swab to blend the mixture into the rest of the sink to create a seamless look.
Allow the sink to dry completely before use.