How to Repair a Chipped Bathtub or Sink (4 Methods That Last)

TL;DR: Clean the chip with acetone, match the repair kit to your fixture material (porcelain enamel kits for cast iron tubs, two-part epoxy for fiberglass and acrylic), apply in thin layers, and cure for 24-48 hours. A DIY fix costs $15-$80 and prevents rust or water damage that leads to a $3,000+ tub replacement.

_Last reviewed: July 2026 · 6 min read_

A chip in your bathtub or sink looks minor until water gets underneath the finish. Cast iron rusts, fiberglass delaminates, and acrylic cracks further—all because a quarter-sized chip let moisture in. Fixing it yourself takes 2 hours and costs less than $80 if you match the repair method to your fixture material.

Okoniq Property Hub logs repair dates and tracks which fixtures need attention, so you know when to check a repair or schedule refinishing.

What type of fixture do you have, and which repair kit matches it?

Bathtubs and sinks are made from four common materials, and each needs a different repair compound. Porcelain-enamel-over-cast-iron tubs (heavy, magnetic base, pre-1980s common) chip down to gray metal and need a two-part porcelain repair kit with hardener and white filler. Fiberglass tubs (lightweight, flexes slightly, 1970s-1990s common) chip to expose woven glass strands and require two-part epoxy resin designed for fiberglass—brands like Bondo or Marine-Tex work. Acrylic tubs (smooth, warm to the touch, non-porous, post-1990s standard) need acrylic-specific repair putty or two-part epoxy labeled for plastic. Cultured marble or solid-surface sinks use gel coat repair kits sold by the manufacturer.

Hardware stores stock Rust-Oleum Tub & Tile Refinishing Kit ($25-$35, includes epoxy and color additives), Homax Tough As Tile ($15-$20, aerosol epoxy for small chips), and Red Devil Porcelain Repair Kit ($12-$18, two-part paste). Read the label—using a porcelain kit on fiberglass won't bond, and fiberglass resin on acrylic can melt the surface.

If your chip is larger than a half-dollar or the fixture has multiple chips, consider full bathtub refinishing instead—pros charge $400-$600 to recoat the entire surface, and the finish lasts 7-10 years. For one or two chips, a kit is faster and cheaper.

How do you clean and prep the chip so the repair sticks?

Wipe the chip with a degreasing dish soap and rinse thoroughly, then dry completely with a lint-free cloth. Use 220-grit sandpaper to rough up the edges of the chip and a half-inch border around it—this gives the epoxy mechanical grip. Wipe away dust with a tack cloth or damp rag, then clean the sanded area with acetone or denatured alcohol on a paper towel (wear nitrile gloves). Let it air-dry for 10 minutes.

Do not skip the acetone step. Soap residue, body oils, and old caulk inhibitors in the water all prevent epoxy from bonding. If the chip exposes bare metal (cast iron), use a small wire brush or 100-grit sandpaper to remove loose rust, then wipe with acetone again.

For deep chips (more than ⅛ inch), fill the cavity in two stages. Apply a first layer, let it cure to touch-dry (1-2 hours depending on kit instructions), then apply a second layer flush with the surface. Overfilling in one pass traps air bubbles and shrinks unevenly.

If the chip is near a drain or faucet where bathroom tile regrouting or caulk replacement is also due, do the chip repair first—grout and caulk can wait, but an open chip lets water in daily.

How do you apply the repair compound and match the color?

Mix two-part epoxy according to the kit instructions (usually 1:1 ratio by volume, stir for 60-90 seconds until uniform). Most kits include white base and tinting powders—add tint in tiny increments (toothpick dips) and test on a paper plate before applying. Almond, biscuit, and bone are common off-white tub colors; match against the fixture's back wall in daylight, not under yellow bathroom bulbs.

Use a small putty knife or plastic spreader to fill the chip, pressing firmly to eliminate air pockets. Overfill slightly—the compound will shrink 5-10% as it cures. Smooth the surface with the spreader in one direction, then let it cure untouched for the time listed on the kit (typically 24-48 hours at 70°F or warmer). Do not use the fixture during this window—shower steam and temperature swings can prevent full hardening.

After curing, wet-sand the repair with 400-grit sandpaper to bring it flush with the surrounding surface. Wipe clean, then polish with 600-grit or 800-grit wet/dry sandpaper in circles. For a glossy finish, buff with automotive rubbing compound on a soft cloth. The repair will be slightly visible up close but invisible from standing height if the color match is close.

If the repair sinks or cracks within a week, the chip wasn't fully cleaned or the epoxy ratio was off. Scrape it out with a razor blade, re-prep, and reapply.

When should you call a pro instead of DIY?

Hire a bathtub refinisher if the chip is on a walking surface (tub floor, shower pan) where foot traffic will crack the repair, if the fixture has more than 3 chips, or if the surrounding finish is flaking or discolored. Refinishers strip the old coating, repair all chips, and spray a new epoxy-acrylic or polyurethane topcoat—the result lasts longer than piecemeal patches. Expect $400-$600 for a standard 5-foot tub, done in one day.

Call a plumber if the chip exposes a crack that goes through the tub wall—fiberglass and acrylic tubs can develop stress fractures from flexing, and epoxy won't stop them from spreading. A through-crack means the fixture needs replacing ($800-$3,000 installed depending on material).

For sinks, chips on the basin rim or faucet deck are cosmetic and worth DIY fixing. Chips on the drain flange or overflow often indicate a loosening drain assembly—tighten the locknut from below or replace the drain before patching the chip.

If you're seeing ceiling water stains below a second-floor bathroom, check for chips around the tub drain and overflow—water wicking under a chipped finish can drip through the subfloor without leaving obvious tub-edge leaks.

FAQ

How long does a bathtub chip repair last?

A properly applied two-part epoxy repair lasts 3-5 years on a non-walking surface (tub wall, sink basin) and 1-2 years on a high-wear area like a tub floor. Refinishing the entire fixture gives a 7-10 year lifespan with normal use.

Can I use nail polish or super glue to fix a chip?

No. Nail polish and cyanoacrylate glue (super glue) are not waterproof under hot water and UV exposure, and they don't bond to porous surfaces like fiberglass or cast iron. They'll peel off within weeks and trap moisture underneath, accelerating rust or mold.

How do I prevent chips in the first place?

Use a rubber mat or non-slip decals in the tub to cushion dropped shampoo bottles. Never use abrasive cleaners (scouring powder, steel wool) on porcelain or acrylic—they scratch the finish and create weak spots. Tighten loose faucet handles and showerheads so they don't fall and impact the fixture.

Will a chip repair stop rust on a cast iron tub?

Yes, if you remove loose rust with sandpaper or a wire brush before applying the epoxy. The repair seals the metal from water and air, halting oxidation. Rust stains around the chip can be removed with a paste of baking soda and hydrogen peroxide (let sit 10 minutes, scrub gently, rinse).

Can I repair a chip in a shower pan or walk-in tub?

Yes, but use a fiberglass-rated epoxy with high compressive strength (Marine-Tex or PC-11 epoxy paste). Shower pans flex under foot weight, so standard porcelain repair kits crack. Cure time is 48-72 hours—cover the repair with a plastic cup to protect it from accidental contact.

This is educational information, not professional contracting advice. For cracks that go through the fixture wall or chips that expose plumbing, consult a licensed plumber before attempting repair.