This Montana chalk spray has the look and feel of a rough chalk effect, ideal for temporary outdoor markings as well as for indoor studio artwork. This is a great medium for signage for events, advertisements, marketing campaigns and outdoor activities. Apply this spray on various surfaces such as sidewalks, walls, Cardboard and canvas. The chalk markings will last from several weeks to several months, depending on climate and weather conditions. The chalk color pigments will wash away faster on non-porous surfaces like glass or metal, but some pigments may remain on porous surfaces.