PU lacquer (two-pack polyurethane, 2K PU) is a paint system of resin and hardener that cross-links chemically after mixing. It is sprayed in multiple coats, sanded between coats, and cures to a film typically 0.3–0.5 mm thick. It is the standard finish for painted custom cabinetry.
How the film is built
It is not one coat. A typical specification is one sealer coat, one or two build coats and one top coat, with sanding between each. The sealer is what stops the board grain and the edge banding from telegraphing through after a few months — skipping it is the most common cause of a finish that looks flat in the factory and rippled on site.
Cure is chemical, not evaporative. Pot life after mixing is a few hours, and full hardness takes several days. A door packed the day after spraying will still be soft at the edges when it is unwrapped.
| Finish | Gloss level | Hides marks | Best for |
|---|---|---|---|
| Matt | 5–10 GU | Poorly — shows fingerprints | Low-traffic, large flat doors |
| Satin | 20–30 GU | Reasonably | General residential |
| Semi-gloss | 40–60 GU | Well | Kitchens, family use |
| High gloss | 85–95 GU | Very well, but shows dust | Feature doors, dark colours |
Why matt is harder than gloss
A matt film uses silica or similar flattening agents, which leave a micro-texture. That texture scatters light — which is what makes the finish look soft — but it also traps oils from hands. A matt black door in a family kitchen will show every fingerprint within a week, and it cannot be wiped to an even sheen.
Gloss is more forgiving of marks and easier to clean, but it amplifies any defect in the substrate. A gloss door sprayed over a poorly sanded edge shows the edge line like a shadow.
What can and cannot be repaired
A scuff or a small chip can be touched in with the same batch of lacquer and blended, provided the sheen matches. This is the practical advantage over melamine and laminate, which cannot be blended at all.
A deep scratch through to the board, or a swollen edge, cannot be repaired on site — the door goes back to a spray booth. Keep a small quantity of the original batch for touch-ups, and record the batch number; a re-spray two years later will not match unless the formula is on file.
Frequently asked questions
Is PU lacquer the same as polyurethane varnish?
No. PU lacquer here means a two-pack sprayed coating for cabinet doors; varnish is a single-pack brush product. They behave differently and are not interchangeable.
How long does a PU finish last?
A properly applied 2K PU film on an interior door typically holds 10–15 years without recoating. Kitchens with heavy use and frequent cleaning sit at the lower end.
Can PU be applied over melamine?
Only with a bonding primer and a sanded key. Direct application to a melamine face will fail at the adhesion layer, usually within a year.
Why does my matt finish mark so easily?
Matt films have a micro-rough surface that traps oils. It is inherent to the sheen, not a defect. Satin or semi-gloss is the practical choice for a working kitchen.
