Appearance of a darker/denser color or higher sheen where two layers overlap during paint application.
Failure to maintain a "wet edge" when painting. Essentially, some areas are receiving 2 coats.
Painting on an unsealed surface.
Painting under high temperatures.
Maintain a wet edge. When painting, apply paint in the unpainted area first and then back into the wet paint surface. This technique will produce a smooth, uniform appearance. Work in manageable-size areas; plan for interruptions at a natural break, such as a window, door, or corner.
Prime the surface with the appropriate primer to prevent the paint from soaking into the surface and drying too quickly.
Begin rolling at a corner near the ceiling and work down the wall in three-foot-square sections.
Spread the paint in an "N" pattern, starting rolling from a dry area into the wet area.
Cross-roll to fill in the "N".
Finish with light, downward, parallel strokes to uniform the finish.