Insta-Blak A-380 is a room temperature immersion finish for aluminum surfaces. Alkaline liquid concentrate used at 25% to 40% by volume in water. Immersion times of 30 seconds to 2 minutes. It is recommended for blackening aluminum objects not requiring a high degree of abrasion resistance such as heat sinks, etc. It is not as hard as a black anodized finish. The hardness of the finish can be enhanced by top coating with a clear lacquer such as EPi’s E-Tec 520.