Touching Up Hairline Cracks in Bathtubs

Fiberglass Tubs

• Fiberglass kits will easily repair a fiberglass tub that shows hairline cracks. A commercial polyester filler will also work to repair cracked fiberglass. Hairline cracks in fiberglass are often hard to see when the tub is wet. Completely dry the surface of the tub so you can visually make out the cracks. Follow the directions on the fiberglass or polyester repair kit. If the crack goes all the way through the tub, you will need to repair the underside of the tub as well.

Finishing Fiberglass Repair

• Once the polyester or fiberglass repair substances dries, you will need to sand the bathtub using various grains of sandpaper. The sandpaper will help create a smooth surface and make the spot that was repaired indistinguishable from the rest of the tub. Once the surface is smooth, paint the tub using an acrylic paint that matches the tub's surface.

Porcelain Repair

• Always wash and dry the tub's surface before undertaking any repair tasks. A slight hairline crack in a porcelain tub can often be hidden by applying paint to the crack. Porcelain enamel paints are widely available at art and craft stores. A deep crack will require filler or caulk before trying to paint and hide the spot. Only use a small amount of filler on the crack. You can apply it using your fingers. Rub the filler across the crack until it cannot be felt by your fingers.

Painting the Porcelain Tub

• Allow the filler to completely dry on the tub's surface. Remove the hardened filler with a razor blade. Run the blade across the surface of any excessive filler and cut it away. The filler should feel smooth to the touch before you can paint it to match the tub's surface. Use a porcelain enamel paint to cover the filler and successfully hide the crack.