Cultured marble is a man-made product created from marble dust and resins, finished with a high-shine gel coat. The resulting product can be molded into shower surrounds, benches and vanity tops and can provide inexpensive elegance to a bathroom design. If the cultured marble becomes chipped, or if holes are drilled and require patching, the same gel coat that gives the product its shine can be used to fill the holes. Most cultured marble colors are available in a gel coat repair kit, which will allow you to fix the hole at home.
Sand down the edges of the chip or hole. Smooth the chip out so no jagged edges remain, and the cavity is clean, dry and ready to receive a patch.
Mix the gel coat patch. Pour a small amount of gel coat into a bowl and add the catalyst and pigments. Mix well with a craft stick until completely blended.
Scoop up some of the patch with the craft stick, and apply it to the chip or hole. The patch will shrink as it dries, so slightly overfill the chip, feathering the patch with the stick onto the edges of the nearby cultured marble. Smooth the top of the patch with the edge of the stick as much as possible. Allow the patch to dry overnight.
Check the patch for shrinking and cracks. If the patch has shrunk too much and exposed a crack around the edges, apply additional patch.
Wet down the finished patch, and sand the area with a fine-grit sandpaper until the patch is smooth and indistinguishable by touch from the surrounding area.
Paint a clear coat of gel onto the patch and surrounding area to restore the shine and blend the patch in with the surrounding area.