I dropped a glass shampoo bottle in the tub and it put a quarter sized chip in the enamel. I left it alone for a month because it seemed cosmetic. Then the chip started to look rusty and I panicked, because rust in a tub means the metal underneath is corroding. The repair kit I bought cost less than a pizza and took an evening.

Why chips spread

Bathtub enamel is a hard coating over metal or porcelain. A chip exposes the layer underneath, and water gets in. Over time the damage spreads under the enamel and turns into a much bigger repair. Fixing it early is the difference between a small kit and a big reglazing bill.

How to patch a chip

1. Clean the chip with rubbing alcohol and let it dry completely. Any soap residue will keep the patch from sticking.
2. Sand the edges lightly with fine sandpaper so the patch has something to grip.
3. Mix and apply the two part epoxy from a tub repair kit. Most kits come with a white paste and a hardener.
4. Fill the chip slightly above the surface, because the epoxy shrinks as it cures.
5. Let it cure for the full time the kit says, usually overnight, then sand it flush with fine sandpaper.

What I wish someone told me

Buy the porcelain repair kit with the little paint pot, not the giant fiberglass patch kit, unless the chip is huge. The paint on patch is enough for normal dings and it dries to a glossy finish that blends in. I used the fiberglass kit on a small chip and spent an hour sanding down the excess.

Match the color in good light. White tubs sound simple until you see that most are off white or cream. Hold the color card against the tub before you mix.

My patch has lasted two years. You can still find it if you look closely, but nobody has ever noticed it without me pointing it out. The rust never came back.