A porcelain sink crack can be stabilized and blended with epoxy; deep, leaking damage calls for replacement.
Small fractures in vitreous china look scary, but many are surface-level and can be sealed so they don’t spread or collect grime. This guide shows you how to judge the damage, choose the right kit, and complete a neat repair that holds up to daily splashes.
Crack Types, Triage, And Best Path
Start with inspection. Light the bowl from the side, run a fingernail across the line, and check around the drain and overflow. Use this table to pick a safe plan:
| Crack Type | What You’ll See | Recommended Action |
|---|---|---|
| Hairline In Glaze | Spider-web lines, no edge you can feel, no moisture wicking | Cosmetic seal and touch-up paint |
| Surface Fracture | Fingernail catches, line grows from impact point | V-groove, fill with two-part epoxy, sand, and topcoat |
| Through Crack/Leak | Moisture below sink, stain trails, movement when pressed | Replace the basin; patching is unsafe |
Close Variation: Fixing A Crack In A Porcelain Sink — What Works
Vitreous china is glassy and hard, so fillers need grip and a waterproof cure. Two-part epoxy paste or putty bonds well, can be sanded smooth, and accepts porcelain touch-up enamel. Cyanoacrylate can seal a pin line fast, but it’s brittle and doesn’t build strength. For a neat, durable blend, go with an epoxy kit designed for tubs, tiles, and basins.
Tools And Materials
Gather the gear before you start so the mix window doesn’t catch you off guard. Lay out:
- Two-part epoxy repair kit (paste or putty) and matching white enamel
- Razor scraper, 220–600 grit sandpaper, and a small file
- Masking tape, microfiber cloths, isopropyl alcohol
- Putty knife or plastic spreader; toothpicks for fine lines
- Nitrile gloves, eye protection, and a fan for airflow
Safety And When To Stop
Leaks below the counter, cracks radiating from the drain, or a line you can flex with light pressure mean the fixture is done. Overtight drain hardware can also start cracks at the rim; major makers warn against cranking down on vitreous china. See the Kohler note about overtightening for context. If any of those signs show up, budget for a swap.
Step-By-Step Repair For A Non-Leaking Crack
1) Prep The Surface
Clear the deck and give the bowl a deep clean. Rinse, then wipe with alcohol to remove soap film. Dry the line with a hair dryer on low. Tape a neat border around the area so you don’t scuff good glaze while sanding.
2) Open A Tiny V-Groove
Use a fresh razor or a fine file to bevel the line just enough for epoxy to key into the glaze. Aim for a shallow V along the crack, not a trench. Vacuum dust and wipe again with alcohol.
3) Mix The Epoxy
Read the label, then blend equal parts on a scrap card until the color turns uniform. You’ll have only a short working time. Split the mix in two so you can apply in thin passes instead of one blob.
4) Fill And Smooth
Press the epoxy into the groove with a plastic spreader. Feather the edges so the ridge is just proud of the glaze. For a fine line, drag a toothpick along the crack, then level with a damp gloved finger.
5) Let It Cure
Keep water off the area for the full cure window on the package. Warm, dry rooms help. Rushing this step leads to haze and soft spots.
6) Sand Flush
Start at 320 grit and move to 600. Use short strokes across the repair and stop the moment you reach the surrounding sheen. Pull the tape and clean dust.
7) Touch Up The Color
Many kits include a porcelain touch-up enamel. Dab thin coats with a fine brush, flashing each coat with a hair dryer. A drop of clear topcoat can bring back the gloss. Loctite shows a clear walk-through for epoxy putty and touch-up steps on its porcelain repair page.
Curing Times And Water Reuse
Resist the urge to test early. Even fast-set epoxies continue to gain strength for a day or more. The table below gives common cure windows; your product rules the timeline.
| Material | Handle Time | Full Water Exposure |
|---|---|---|
| 5-Minute Epoxy Paste | 20–60 minutes | 24 hours |
| Epoxy Putty Stick | 30–90 minutes | 12–24 hours |
| Touch-Up Enamel | 1–2 hours between coats | 24–72 hours |
Color Match Tips
Whites vary by brand and age. Test a dot of enamel on tape first. If it’s too bright, add a tiny speck of light gray from a tile-touch-up pen to mute the tone. Blend along a panel line rather than stopping in the middle of a flat field; that trick hides the repair.
Fixes Around The Drain
Lines that start at the drain ring often point to mechanical stress. Back off the locknut from below, set a thin bead of plumber’s putty, and retighten only to snug. Don’t wrench down on glassy china. A warning from Kohler across many install guides repeats this point about overtightening on vitreous parts.
Prevent New Cracks
- Skip boiling water in the bowl; rapid swings in temperature can shock the glaze.
- Use a soft mat when handling tools over the sink.
- Set the drain snug, not tight; recheck once a season.
- Keep harsh acid cleaners out of the bowl; mild bathroom cleaner and a non-scratch pad is enough.
When Replacement Beats Repair
Choose a new basin when you see leaks, movement across the line, a crack through the overflow, or heavy crazing across the bowl. Patching those cases wastes time and can lead to cabinet damage. Drop-in and undermount sinks are widely available and a straight swap for most cutouts.
Quick Troubleshooting
Epoxy Won’t Stick
Film from soap or wax blocks adhesion. Degrease with alcohol, scuff lightly, and try again with fresh mix.
Repair Looks Dull
Sand marks create haze. Step up to 1000-2000 grit wet/dry paper, then finish with a dab of clear enamel.
Line Keeps Growing
Hidden stress is at work. Remove the drain ring, check for overtight hardware, and plan for a new basin if the line runs when pressure is applied.
Cost, Time, And Skill Level
A DIY kit runs a small sum and the job fits a weekend afternoon. Most of the time lands in waiting for cure. If you want a like-new finish on an older pedestal sink, a refinisher can spray the whole bowl; that route costs more but hides repairs across a wide field.
Method Recap
Inspect first, choose epoxy, open a shallow groove, fill in thin passes, cure fully, sand flush, and finish with touch-up enamel. Used on a non-leaking line, this process keeps water out of the crack and prevents stains from creeping into the glaze.
Porcelain, Ceramic, And Enamel — What You’re Repairing
Bathroom basins sold as “porcelain” are usually vitreous china: a ceramic body with a fired glass coating. That glaze is tough and glossy, yet thin. Chips expose a dull, porous body that wicks stains; that’s why filling and sealing matter. Fireclay sinks share a similar makeup and take the same kind of kit. Enameled steel and cast-iron have a metal core with a glass skin; small chips on those can be filled and touched up with the same approach, though they dent rather than crack.
Pre-Work Checklist
- Confirm there’s no drip under the counter or pedestal.
- Photograph the line in daylight; zoom shows whether the edge is open.
- Set a timer for the epoxy pot life so you don’t rush.
- Cover the drain with tape so filler doesn’t drop through.
- Place a towel in the bowl to protect the surface between steps.
Aftercare And Longevity
Give the repair a day before full sink use, then treat it gently for a week. Use a non-abrasive cleaner, wipe dry after toothpaste and soaps, and avoid scouring pads on the patch. A thin coat of liquid carnauba wax on the bowl (not the patch) can help water bead and carry grit away during daily use. If the line reappears, a light sand and one more thin coat of enamel refreshes the blend without another full fill.
When You Call A Pro
A refinishing tech can color-match and spray the entire interior for a uniform sheen. That route shines when a pedestal or vintage lav has wide crazing yet solid structure. The process uses catalyzed coatings and proper ventilation, so it’s shop-grade work. For a leaking bowl or a split across the overflow, a plumber can replace the unit once water lines and the trap are loose.