Pebeo Drawing Gum is suitable for use with all water-based media. Don’t let the name fool you, Pebeo Drawing Gum is a masking fluid that can be used with a paintbrush or with a masking fluid pen. It can be used to block out areas where you don’t want paint, ink or airbrush to appear. It thins with water and is easily removed. This masking fluid dies to a light grey color so it’s easy to find when its time to remove to reveal those whites.