This Schmincke Liquid Frisket Medium is blue in colour so that you can easily see the areas that you have masked off to stay white when painting with Watercolour Paints. It is a removable gum emulsion. Apply Liquid Frisket (also known as Masking Fluid) directly to areas that you dont want the paint to cover. Once dry, you can then paint over the medium and the surface underneath will remain paint free. Remove the Schmincke Liquid Frisket Medium as soon as possible. Once your painting is finished and dry, simply rub off the masking fluid with your finger or an eraser. Does not contain ammonia. 20ml Bottle.