Schmincke : Masking Fluid

Schmincke Masking Fluid is a liquid gum used to mask off areas you want to keep white while painting with watercolor. It can be applied undiluted with a brush, dip pen, cotton bud, or spatula to watercolor paper, smooth drawing card, photos, or film. Once dry, you can paint over it. When your painting is finished, the dried masking fluid can be gently rubbed off with your finger or an eraser.

For best results, remove it within 2 days to avoid damage or staining. A slight yellowing may occur depending on the paper. Always clean your tools with water and soap right after use. Be sure to close the bottle tightly and protect it from frost.