Picture Framing
An appearance issue where the brushed areas of a paint coating generally appear darker, resembling the 'frame' of a 'picture.' Sprayed areas are also often darker than neighbouring sections that are brushed or rolled.
Possible Cause
Usually a hiding (coverage) effect. Brushing will generally result in lower spread rates than rolling, producing a thicker film and more hiding
Adding colourant to a non-tintable paint, or using the wrong type, or level, of colourant
Solution
Make sure that spread rates with brushes and rollers are similar. Don't cut in the entire room before roller coating. Work in smaller sections of the room to maintain a 'wet edge.'
With tinted paints, be sure the correct colourant-base combinations are used. Factory colours, as well as in-store tints, should be thoroughly shaken at time of sale, and the product must be thoroughly stirred prior to use.
More problem solving advice
Yellowing describes the development of a yellow cast in ageing paint solvent-based enamels.
Wrinkling is a term to describe a rough, crinkled paint surface, which occurs when uncured paint forms a 'skin'.
Sagging is the downward "drooping" movement of the paint film immediately after application that results in an uneven coating.