Draining may leave stains on paint film, especially on the top edge of walls, terrace rails, eaves, and etc., distracting the aesthetics of the building. These stains exist when dust or pollution accumulated on top of building or in corners of the walls is being drained down with rains. The stains tend to remain on the surface and absorb down into paint film if no proper solutions have been taken.
Draining marks can be washed or coated, but they can exist again as long as dust remain and being drained by rains. Solutions of draining marks include adjusting the roof slope to bend into one side; using shiny paint with extra thick film to prevent stains from absorbing into the paint. Alternatively, use downspout gooseneck to prevent downpour from the roof. Once the drain is adjusted, wash out the stains and refinish.