A lightly tinted liquid, used to temporarily mask and preserve the paper when applying colour, as it prevents the paint adhering to the paper. Especially useful when trying to create fine details. Do not apply on damp or soft sized paper. Remove as soon as possible after application. Brushes can be cleaned with water if washed immediately after use.

Masking Fluid creates physical boundaries in a watercolour painting. This makes it ideal for playing with negative space in a composition. I’d use this for expressionistic effect, and of course it is effective for defining blocks of colour, horizons or leaving areas white, before painting at a later stage.