Fast, inexpensive alternative to black oxide. Imparts a tough, dull black protective finish to ferrous metal parts. Ideal for prototypes, repair parts and general machine work. The Gel formula is best for larger areas or fixed vertical spaces. Should be used at room temperature as a cold application. One pint of Tool Black® Gel covers 20 sq-ft, however coverage varies with application technique. Tool Black® products cannot be shipped via air transportation. Precision Brand® Tool Black® Tool Black Gel, 1 pt Container, Bottle Container, Liquid Form, Blue, 20 sq-ft Coverage, Chemical Composition: Water, Nitric Acid and Selenious Acid, 1 pH, Odorless Odor/Scent