How do I stop brush marks in gloss paint?

Gloss levels itself if you let it. Every gloss paint has an open time — the window in which it is still fluid enough to flow out — and brush marks are what happens when a brush touches it after that window has closed. Water-based gloss has a notably shorter open time than traditional oil-based gloss, which is the single biggest reason people who used to get good results now do not.

Step by step

1. Use a decent brush and keep it for gloss only.A good synthetic filament brush for water-based gloss, or natural bristle for oil-based. A brush that has had emulsion in it holds dried paint in the heel and will comb the finish however well you wash it.
2. Prepare properly, because gloss hides nothing.Gloss is the least forgiving finish there is. Every ridge, nib and sanding scratch is amplified by the reflection. The surface has to be flat and uniformly keyed before any paint goes near it.
3. Load the brush by dipping a third of the bristle depth.Too little paint and you are dragging a dry brush, which is guaranteed to leave marks. Too much and it runs. A third of the bristle, tapped rather than scraped against the side of the tin.
4. Spread the paint on quickly, without trying to make it neat.Get the right amount of paint onto the area in a few strokes. This stage is about distribution, not appearance. Speed matters because everything after it has to happen inside the open time.
5. Level it across the work, then lay off along it.Work the paint out sideways to even the thickness, then finish with long light strokes in one direction, following the length of the piece. Laying off is done with the tips of the bristles and almost no pressure.
6. Stop touching it.This is the hardest part and the most important. Once you have laid off, walk away. A brush going back into setting gloss to fix a small mark creates a larger one, and each attempt at rescue makes it worse.
7. Work in manageable sections and keep a wet edge.Never let the edge of the painted area dry before you join the next section to it. On a panel door that means working panel by panel in a set order rather than in random patches.
8. Sand lightly between coats and remove the dust properly.A light abrasion knocks off nibs and gives the next coat something to key to. Then take the dust off with a tack cloth or a barely damp lint-free rag — dust in the film reads as texture, not as brush marks, but people blame the brush.

Tips

• Warm rooms and draughts both shorten open time. A hot day with the window open is the worst combination for water-based gloss.
• If the paint is dragging within seconds, it is not your technique — the conditions are wrong, or the tin is old and thickening.
• A small foam roller followed immediately by laying off with a brush gives a very even film on flat panels.

Common mistakes

• Going back to fix a mark five minutes later. — The film has begun to set. The brush tears it rather than smoothing it, and the repair is always more visible than the original mark.
• Thinning gloss to make it flow. — It changes the film and can affect durability and gloss level. Deal with open time by working faster and in better conditions instead.
• Using a brush that has emulsion dried in the heel. — Hardened paint at the base of the bristles splays them and leaves tramlines however carefully you work.

Questions people ask