Ideal for Sanding by Hand or Machine SandingOur 3M™ Paper 336U is available in grades of 100, 120 and 150. A resin bonding helps to resist heat and the C-weight paper backing is tear resistant yet can be easily cut to fit any work piece or hand tool for the task at hand. Aluminum oxide is the mineral of choice for a wide variety of applications on many substrates. It is a long-lived, durable abrasive that self-fractures to expose fresh cutting edges, keeping it sharper longer than many other abrasives. This sheet features an open coat aluminum oxide mineral to help reduce loading and deliver longer service life. When an Open Coat is Highly DesirableAbrasives cut better and last longer when dust isn’t clogging the cutting surface of the abrasives. Open coat construction means the abrasive grains are less densely spaced on the backing, allowing sawdust to be evacuated and keeping cutting mineral free. This allows the sheet to continue cutting even when sanding soft metals and surfaces that would, otherwise, clog the grain and hinder sanding ability. Recommended ApplicationsThis sheet is well suited for prepping metal prior to paint and sanding soft metals like aluminum, brass, bronze and copper in hand sanding applications.