solvent poping

force drying,like with a fan can cause this also,or if the painter is just too plain anxious and in a hurry,they will not give the paint enough time to "flash".So when they apply a coat over the coat that has not yet flashed,the solvents come up from the coat that has not had time to gas out through the new coat so that makes the little air blisters in the paint.Sometimes you can buff it out .