Applying Masking Fluid
Soap the bristles of your brush before dipping it into the masking fluid. Masking fluid is similar to rubber cement, and the soap protects the bristles and keeps them from sticking together. It is very important to wash the brush with more soap and water immediately after you are through using the masking fluid.
Removing Dry Masking Fluid
To remove a mask use a hardened rubber cement-like eraser that is made specifcally for this purpose. The mask can also be removed by rubbing it off with your fingers.