It is use to create striking white highlights or/and areas to overpainting at later stage.
It forms a fast drying and waterresistant-film on watercolor paper or board.
It’s easily remove when it’s dry by using an eraser to rub or a soft tissue or perhaps a cotton bud!
It’s advisable to use an old pen or brush or cotton bud to apply Watercolour Masking Fluid as it’s otherwise quite difficult to remove it when dry especially on brushes.