Masking fluid, also known as liquid frisket, is a very handy tool for fine art water colorists to preserve white areas that would be too tiny or complex to paint around. What is masking fluid, exactly? It’s made of a suspension of latex in water and is usually lightly tinted to make it easier to see on the paper, either a light yellow or gray. Ammonia is added as a preservative. Here are some tips for using masking fluid: 1. Before using masking fluid you need to have your painting all planned so you know exactly where the highlights or areas you will want to preserve are. Tiny areas in this painting are preserved with masking fluid.Tiny areas in this painting are preserved with masking fluid. 2. Never shake the bottle, as it will cause the product to lump and you might get tiny air bubbles in the fluid. You can stir it gently. Rubbing a brush on a bar of soap to clean Rubbing a brush on a bar of soap before painting with masking fluid. 3. Use an old bru...