What is masking fluid?

Masking fluid is a liquid substance that is applied to watercolor paper or any other absorbent surface to temporarily protect certain areas from watercolor paint. It is commonly used in watercolor painting to preserve areas of white or light colors on the painting surface, which the artist does not want to be painted on. Masking fluid can be easily removed once the painting is complete, revealing the untouched areas of the paper. It is available in different colors and can be applied to any surface using a brush or pen. However, it should be noted that masking fluid can sometimes damage the paper or leave behind stains, so it is recommended to test it on a small patch of the paper before applying it to the entire painting surface.