Short answer
Do not paint over loose laminate or thermofoil. The paint will lift with the loose material. First remove the loose material, then repair and smooth the surface. Prime with a bonding primer, and paint two thin coats of cabinet enamel. If thermofoil is lifting from heat, or the particleboard has swollen from water, the door or panel may need replacing rather than repairing.
First, work out what is peeling
The fix depends on what is coming away.
- Thermofoil (a vinyl wrap) lifting from MDF. This is common on doors near the hob, kettle, toaster or dishwasher, where heat drives the failure.
- HPL or melamine delaminating. The laminate separates from its core, often at edges or seams.
- Old paint peeling from laminate. The paint was applied without a bonding primer and has come away.
Why thermofoil peels
Heat and steam weaken the adhesive that holds the vinyl wrap to the MDF. Once a section lifts, paint cannot bond to it. Painting over a lifting wrap will not glue it down, so remove the wrap or replace the door.
Remove the loose material
- Warm the wrap. Use a heat gun on low, or a hair dryer, to soften the adhesive.
- Peel slowly. Lift the wrap gradually and keep the heat moving. Stop if the MDF begins to scorch.
- Clean off the adhesive. Use mineral spirits or an adhesive remover.
- Sand the MDF. Use 150 to 220 grit to smooth the surface.
Heat guns can ignite solvent vapours and dust, so keep solvents away, do not overheat the surface, and work well away from open flames. Wear a respirator when sanding MDF, because its dust is resin-bonded.
Repair and smooth the surface
- Fill gaps, chips and drop-offs with a wood filler, a two-part filler or a spackling compound. What is the best wood crack filler compares them.
- Sand the repairs flush once they are dry, then wipe away the dust.
- Pay attention to edges. Cut and routed MDF edges are porous and need more primer than flat faces.
Reglue small lifted edges
If a laminate edge is only slightly lifted, you can reglue it instead of removing it.
- Apply contact cement to both the cabinet surface and the back of the laminate.
- Let the cement become tacky, following the label, then press the pieces together.
- Roll the laminate firmly with a J-roller, then clamp or weigh it down while the adhesive sets.
Some guides suggest wood glue for this. Use contact cement instead, because wood glue is not designed to bond laminate.
Remove old peeling paint
Scrape off all the loose paint, feather the edges with 150 to 220 grit, then degrease and rinse. Paint that is only partly loose must be taken back to firm material. More coats will not fix poor adhesion.
Prime with a bonding primer
A bonding primer is the step most often missing from a failed repaint.
- On laminate or old paint, use a bonding primer such as Zinsser B-I-N (shellac), INSL-X Stix, Sherwin-Williams Extreme Bond or Zinsser Cover Stain (oil).
- On bare MDF or particleboard, use a shellac or oil primer. Edges may need two coats, with a light sand between them.
- Let it cure. Some waterborne bonding primers need days to reach full adhesion. Follow the label before you topcoat.
Standard latex primer is not a bonding primer, and it will not hold on slick laminate.
Paint
Apply two thin coats of cabinet enamel. Use a foam roller on flat areas and a synthetic brush in profiles. Let each coat dry before the next.
When to replace instead
Some damage cannot be repaired.
- Particleboard that has swollen from water does not recover. Replace the door or panel.
- Thermofoil lifting across much of the surface is hard to save, and replacement is often the better choice.
- Doors with repeated heat damage may keep failing in the same places.
Common mistakes
- Painting over loose laminate. It does not glue the material down.
- Adding more coats. Extra paint does not fix poor adhesion. Strip back to sound material.
- Using standard latex primer. It is not a bonding primer.
- Trying to sand thermofoil that is still bonded only at the edges. Remove the lifting material first.
Safety
- Heat guns can ignite solvent vapours and dust. Keep solvents away and do not overheat the surface.
- Wear a respirator when sanding MDF.