Repair cultured marble using an epoxy gel-coat finish. Prevent damage to the original gel coat by avoiding the use of abrasive cleaning products, such as scouring powders, when cleaning cultured marble.
Prepare the sink for the repair by washing it and allowing it to air dry. Use a lint-free cloth to remove any dust from the surface after it is dry.
Use a razor blade knife, and dig out the chip. Use the knife to ensure that the edges of the hole are even with the surface of the counter.
Place approximately 1 1/2 ounces of the gel coat in a paper cup, and add 10 drops of the catalyst. Mix well, add a pinch of the white titanium oxide powder from the gel coat, and continue mixing until it is smooth and free of lumps. For dark colors of cultured marble, use a kit specifically formulated for the color.
Use the tip of a toothpick to transfer the gel coat to the hole. Continue adding more of the mixture until it stands slightly above the surface of the counter to allow for shrinkage. Allow the patch to dry from four to 24 hours.
Wrap a piece of 1200-grit wet-dry sandpaper around a sanding block. Wet the paper, and sand the repair so it is smooth. Avoid over sanding the countertop, which can result in more damage. Polish the repair with a buffing compound to restore the shine.