Lapping is the appearance of a denser colour or increased gloss where wet and dry layers overlap during paint application.
- Failure to maintain a 'wet edge' when painting
- Use of a low solids 'economy' paint
Maintain a wet edge when painting by applying paint toward the unpainted area and then back into the just-painted surface. This technique (brushing or rolling from 'wet to dry,' rather than vice versa) will produce a smooth, uniform appearance.
It is also advised to work in manageable-size areas and plan for interruptions at a natural break, such as a window, door or corner. Using a top quality water-based paint makes it easier to avoid lapping problems because higher solids (pigments and binder) content makes lapped areas less noticeable.
If substrate is very porous, it may need a primer/sealer to prevent paint from drying too quickly, reducing wet edge time and therefore making lapped areas noticeable. Solvent-based paints generally have superior wet edge properties, and therefore less lapping.
More problem solving advice
Have you noticed small droplets appearing on your fresh coat of acrylic paint? Don't panic – it’s a normal part of the curing process. Find out more.