Dr. Ph. Martin's Pen-White is perfect for fine writing, and was made to be used in technical pens and airbrushes. This liquid product delivers the same brightness and permanency of traditional watercolors in tubes, but is much more versatile and easy to use. It will also adhere to a variety of surfaces that include film and acetate-type material.Details:White1 fl. oz. (29.57 mL)18 bottlesNon-waterproofConforms to ASTM D-4236 standards