Cause
Problems of this nature can be caused by rain falling onto the semi dried coating or aeration/frothing of the paint during application usually by roller and not flowing out properly. Also referred to as pin holes
Once the coating is completely through dry, flatting down should take place using carborundum (wet or dry) abrasive paper preferably wet – using water/soap or white spirit as a lubricant. Recoat with chosen paint finish.