Schmincke Medium 20 ml Masking fluid white
Making Fluid, also known as masking fluid, is a liquid medium used for watercolor painting.
You apply masking fluid where you don't want to color the paper, leaving white, untouched areas in your watercolor drawing. Masking fluid dries to a glossy rubbery mass and can be rubbed off with your finger afterwards.
Do not leave Masking fluid on for more than 1 day, do not use a brush to apply it as this will ruin it, and never paint on the watercolor before it is completely dry.