Winsor & Newton Watercolour Art Masking Fluid creates a temporary cover to protect areas of work when you’re creating watercolour washes. made from rubber latex with pigment, it can be applied with a brush (though be careful to clean this immediately) & dries to a film that’s easy to peel or rub off when dry. It shouldn’t be applied to damp paper. Winsor & Newton Watercolour Art Masking Fluid is an essential for any watercolourist.