Melamine is a common covering used by cabinet and furniture makers because of its smooth, hard surface. Having a crack, chip or scratch in a melamine door is unsightly. To repair these imperfections, you can use all-purpose putty followed by melamine paint. You can find melamine paint at most home-improvement stores. If your store does not carry the paint, consider purchasing it online.
Remove the door from its hinges and set it on a flat surface in a well-ventilated area.
Mix trisodium phosphate in a bucket with the amount of water recommended by the manufacturer. Use a rag soaked in the mixture to clean off any dirt or grease on the door.
Apply all-purpose putty to any deep cracks, scratches or chips with a putty knife. Allow the putty to dry.
Sand the door with 100-grit sandpaper to give the primer a good bonding surface. Wipe away any dust with a rag.
Use a roller to apply one coat of primer to the door. Allow the primer to dry completely; it typically takes about four hours.
Sand the door lightly with 200-grit sandpaper. Wipe away any dust with a rag.
Apply three thin coats of paint to the door with a roller. Use even pressure and movements to ensure a smooth surface. Allow each coat to dry before applying another.
Allow the door to cure overnight. Be careful with the melamine surface while rehanging the door; it can take up to four days for the surface to harden completely.