Shake well before use: Otherwise, especially where spread thin, it will be impossible to rub off when dry.
Don’t leave it on too long! More than 48 hours, and it gets tricky to remove….
Make sure the paper is completely dry and don’t let water come in contact with the masking fluid otherwise it will sink into the paper and be really difficult to remove later. If you use it on thin, smooth paper (like printer paper) it doesn’t work so well and is really hard to rub off.
Use synthetic brushes that you keep only for masking fluid. To stop the masking fluid from drying onto the bristles, dip the brush in very soapy water, wipe away excess, dip in masking fluid – repeat for each stroke.
Better to mask over plain paper, if you mask over an already painted area you might lift off the paint.
Youtube video: Winsor & Newton Art Masking Fluid
I used masking fluid on this bug picture…