Ans. Yes, you can use masking fluid when painting watercolor trees. Masking fluid is a liquid that can be applied to the paper before painting to preserve areas that you want to remain white or untouched by paint. It can be particularly useful when painting intricate details like branches or thin leaves. Apply the masking fluid with a brush or a fine-tipped applicator and allow it to dry completely before applying the watercolor paint. Once the painting is dry, gently remove the masking fluid with an eraser or your fingertips.