A pale yellow tinted liquid used to temporarily mask the paper when applying subsequent washes of color. It prevents the paint adhering to the paper and the yellow tint helps you see where you are applying the masking fluid to the paper. Dries to a removable, water-impervious film. Especially useful when trying to create fine details. Do not apply on damp or soft sized paper. Remove as soon as possible after application. Brushes can be cleaned with water if washed immediately after use.