Have you noticed that there are areas of denser colour or higher gloss where wet and dry layers overlap during painting?
This is caused by not maintaining a ‘wet edge’ while painting.
To maintain a wet edge, apply your paint towards the unpainted area and then back into the just-painted surface. Brushing from "wet to dry," rather than the other way around will help produce a smooth, uniform appearance. It’s also wise to minimise the area being painted 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? This is known as 'surfactant leaching'. Don't panic - it's a normal part of the curing process. For each problem you’ll find a guide to identifying it, its causes and solutions.
Yellowing is the development of a yellow cast in aging solvent-based enamels. It’s most noticeable in the dried films of white paints or clear varnishes. For each problem you’ll find a guide to identifying it, its causes and solutions.