For use with Watercolour, Art Masking Fluid is used to create striking white highlights or areas for overpainting at a later stage. It forms a fast-drying, water-resistent film on watercolour paper or board and is easily removed when dry by rubbing with an eraser, soft tissue or cotton bud. An old brush, pen or cotton bud should be used to apply the Masking Fluid as it is extremely difficult to remove from brushes when dry.