Lap marks refer to differences in the sheen and colour of paint. Lap marks usually appear as higher gloss or denser colour than the rest of the wall.
Lap marks occur when dry and wet layers overlap during the painting process. Lap marks are more likely to occur if the paint is applied in direct sunlight or in a warm room, and they can also happen if the painting surface is too porous.
As always, it’s important to use high quality paint and tools for your paint job. Ensure to always maintain a “wet edge” to your painting area and use a wet to dry technique. Painting in small sections will make this easier. Additionally, avoid painting on a very sunny or overly windy day, as this will make your paint dry faster. If your painting surface is porous, begin with a primer and keep in mind that you may require two coats of paint.
In order to get rid of existing lap marks, simply repaint over the area, being sure to spread the paint uniformly.