CAUSES: improper or no priming of porous surfaces of surfaces with non-uniform porosity. Poor painting techniques. Painting over fresh paint or primer before it’s dry. Uneven film thickness causes poor sheen uniformity. Drying during excessive high/low temperature.
An additional causes of checking is wallcovering paste that was not completely removed when wallcovering was stripped and the area painted over.
SOLUTIONS: Always prime new work to make the surface have uniform porosity. Apply the finish coat after proper drying of primer. A new finish coat usually will make the sheen uniform. Always paint from went to dry and maintain a wet edge to avoid lapping.