In the spray painting of houses, a vertical masking element is temporarily attached to a storm sash frame or channel and protects the same and adjacent window pane areas from the paint spray. A right angular horizontal masking element is handheld by the painter and protects horizontal sections of the storm sash frame or channel while allowing freedom of one hand for spray painting of surrounding areas. The masking elements embody reusable body portions of sheet metal or the like and replaceable cardboard extensions applied to the reusable components with adhesive tape. The invention effects a major saving in time compared to prior art systems.