(The formation of bubbles or pimples on the painted surface caused by moisture in the wood, by painting before the previous coat has dried).
Bubbles resulting from localized loss of adhesion and lifting of the paint film from the underlying surface. There are 2 kinds of blistering, caused by heat and caused by moisture. Caused by heat: Painting on a surface hat is too warm will cause the film to dry too rapidly, and trap solvent that later vaporize. This will create pressure against the topcoat creating blistering. Caused by moisture: Alkyd finishes are sealer type finishes and do not allow moisture to vaporize. High temperatures, during the summer, will cause moisture to vaporize faster than the alkyd finish coats will allow this moisture to escape.