Selling Acrylicos Vallejo Liquid Mask 17 ml used to model kit's surface area which are want to remain unpainted, especially in airbrush techniques, but also with watercolors, and temperas. Vallejo Liquid Mask forms a protective film on the area which you does not want to paint. Once it is dry, rub off Liquid Mask with an eraser or piece of cloth, revealing unpainted area.