Winsor & Newton Permanent Masking Medium is a non-removable, water repellent liquid wax designed for masking specific areas of paper, making them resistant to water. When dry, the medium will repel superimposed washes. Excellent for detail.

Permanent Masking Medium can be applied directly to white paper, to dried washes on the paper or mixed with water colours first. All water colour washes mixed with Permanent Masking Medium remain open and workable whilst the wash is still wet. Once dry, the area becomes isolated and cannot be fully penetrated by further washes. Brushes should be washed in warm water and soapy water before using other colours. Sections which have been treated with Permanent Masking Medium must be allowed to dry before overpainting. A hair dryer can be used to speed the drying.