Cu/SCRUB 4F-9.1 is an acidified pumice scrub designed to promote cleaning and micro-roughening of copper laminate. Cu/SCRUB 4F-9.1 is formulated with 4F Grade, friable pumice and contains antioxidant components to inhibit cupric oxide formation after the cleaning cycle. During use, fractured particles from friable pumice continue to present sharp cutting edges rather than rounding off, thereby assuring a long and consistent operating life. Cu/SCRUB 4F-9.1 also exhibits a low concentration of free silica and is therefore safer to work with than traditional pumice.