A scratch in a porcelain sink is unsightly, but can be repaired with some patience and a few basic materials you can find at any home improvement center. Even though the scratch may still be apparent, it will be much less apparent when it is carefully repaired and painted to match the surrounding porcelain.
Step 1: Clean the porcelain sink, focusing on the scratched area, with distilled alcohol. Scrub away any soap scum or other residue before proceeding.
Step 2: Use a damp rag to wipe away any residue around the scratch, then use a dry towel to dry the sink.
Step 3: Mix some two part epoxy suitable for use on porcelain according to the manufacturer’s directions. Only mix as much epoxy as you will need for this specific project with a small allowance for waste: epoxy once mixed cannot be saved for later uses.
TIP: For small patches like this, be sure to use a small container that will allow you to adequately mix the epoxy together. A large container will encourage too much waste: for most scratches you should seek to make only a tablespoon of epoxy to fill the scratch.
Step 4: Apply the epoxy to the scratch using a toothpick. Go carefully, filling the scratch in the porcelain crack with epoxy, but not spreading the epoxy to the surface of the porcelain.
TIP: Often when patching an object, you want to feather the edges to blend the patch with the surrounding material. Avoid this inclination while repairing your sink. Instead, you should seek to fill the crack, but no more.
Step 5: Smooth the surface of the epoxy patch with a damp cosmetic sponge. Work quickly to smooth the epoxy as thoroughly as possible without drawing the epoxy out of the crack. Allow the epoxy to cure for 24 hours before proceeding, or the maximum required curing time recommended by the manufacturer.
Step 6: Paint over the patched scratch with porcelain paint purchased to match your particular sink. Use a very fine brush, and attempt to paint the scratch only, not the surrounding, undamaged area of the sink. Let the paint dry for 24 hours before using the sink once more.