How to Repair a Bath: Step-by-Step Guide to Fixing Chips, Cracks, and Scratches

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Your repair method depends entirely on the surface: acrylic scratches get wet-sanded with 400- then 600-grit paper, porcelain chips get a matched glaze, and Vikrell damage needs Kohler’s resin kit.

One wrong abrasive turns a hairline scratch on an acrylic tub into a permanent dull patch. What works depends on three things: the tub material, how deep the damage goes, and whether water can get underneath. Get the material wrong and even a careful repair can make things worse.

The steps below come from Kohler’s own service documentation for acrylic and Vikrell surfaces, plus Sterling’s care guidance for acrylic. Deep cracks, structural damage, and anything letting water through need the manufacturer or a surface-repair pro — not a DIY kit.

How Do You Know Which Bath Surface You Have?

Match the repair to the material before you buy anything, because acrylic, porcelain, and Vikrell each take different products and different grits.

Acrylic is a molded plastic that scratches and dulls relatively easily but responds well to sanding and polishing. Porcelain is glazed ceramic — hard and chip-prone, repaired with a color-matched glaze rather than sandpaper. Vikrell is Kohler’s compression-molded composite, and its repair kit is strictly limited to minor surface scratches, gouges, voids, and chips.

Kohler’s Vikrell instructions explicitly prohibit using the kit for cracks caused by structural damage, and prohibit air-dry spot putty for structural cracks. If you’re unsure of your tub’s material, check the manufacturer’s spec page or the label under the basin before starting.

How to Fix Minor Scratches on an Acrylic Bath

  1. Clean and dry the damaged area.
  2. Sand with 400-grit sandpaper, using flat, even pressure in a circular pattern.
  3. Inspect frequently; clean or replace the paper as it clogs.
  4. Polish the repaired area and its surroundings with clean 600-grit sandpaper, steady circular motion.
  5. Rinse away sanding dust with clean water, then dry with a clean cloth.

Kohler’s procedure is not suitable for deep scratches, gouges, or chips — those go to Kohler or a local solid-surface repair professional. On the success side, the scratch should stop catching your fingernail and the surface should read even under light. For dull or lightly scratched acrylic, Sterling recommends white automotive polishing compound on a clean cloth, rubbed into the area and wiped clean. Kohler also describes automotive rubbing compound followed by paste wax for dull acrylic, but never wax areas where people stand or walk — slip risk.

Skip abrasive cleansers on acrylic entirely; Kohler warns they scratch and dull the surface. Warm water and a liquid, non-abrasive detergent are the recommended clean. Sterling adds that a soft, damp sponge after each use keeps acrylic looking newer, and abrasive brushes or scouring pads should never touch it.

Touching Up Porcelain Chips and Scratches

Porcelain chips and scratches take a compatible repair glaze applied in thin coats, not sandpaper. Clean and dry the defect first, remove any loose material, and lightly smooth the edges with finishing paper.

Brush on thin coats of correctly matched glaze, letting each layer dry per the product label. Drying time, cure time, and coverage vary by brand, so follow the label rather than a general rule. Color match matters more on porcelain than anywhere else — a close-but-wrong shade is more visible than the chip was.

Repairing Vikrell Chips and Gouges With Kohler’s Kit

Vikrell repairs require a specific sequence: rigid polyester filler, a glass-cleaner wipe, then a resin color coat sprayed at low pressure. Automotive body filler is not approved.

  1. Wet-sand with 600-grit or finer paper — never coarse sandpaper.
  2. Remove loose material, then clean a 10-inch (254 mm) area around the defect with acetone or lacquer thinner.
  3. Wet-sand about 1 inch (25 mm) around the defect in circular motions.
  4. Fill and level with premium rigid polyester filler that requires cream hardener.
  5. Let the filler set per its instructions; wet-sand excess and add thin layers if shrinkage or sanding marks remain.
  6. Clean with glass cleaner before painting — Kohler warns paint may fail to adhere and rub off later if this step is skipped.
  7. Mix one part Vikrell Resin COLOR with one part Vikrell Catalyst.
  8. Spray the color coat 1 inch (25 mm) beyond the sanded area at 5–15 psi (34–103 kPa), up to five coats with at least 10 seconds between them.
  9. Hold the airbrush 6–8 inches (152–203 mm) from the surface for color and Repair Blender.
  10. Dry with a heat gun or hair dryer from 6–8 inches away, applying heat for at least 3 minutes.
  11. Let the repair cool, then wet-sand edges with 2,000-grit paper. No buffing compound directly on the repair.
  12. Allow 60–90 minutes of drying, then cure 24 hours at 70°F (21°C) and 50% relative humidity before using the shower.

The Kohler Vikrell Repair Kit instructions cover only minor surface scratches, gouges, voids, and chips. Structural cracks are out of scope for the kit.

If you’d rather start with a complete kit than source filler, catalyst, and color resin separately, this roundup of tested bath repair kits covers what’s actually in each one.

When to Call a Professional Instead

Deep cracks, structural damage, deep gouges, and any damage that lets water penetrate should go to the manufacturer or a qualified surface-repair professional. Water getting behind acrylic or composite can delaminate the surface and turn a small fix into a tub replacement.

Kohler’s own guidance draws the same line: its acrylic instructions are not suitable for deep scratches, gouges, or chips, and its Vikrell kit is prohibited for structural cracks. Recognizing that boundary early protects both the tub and your warranty.

References & Sources

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