Pumie® works best in the presence of a liquid: water, oil or acid. Uses: Food service chefs, painters, plumbers, farmers, mechanics, pool servicers, the industrial cleaning and maintenance trade all depend on the abrasive cleaning action of pumice to remove baked-on food and grease, water and acid stains, rock-hard mineral deposits, paint, rust, lime and other substances from hard surfaces. Do not use on soft, highly polished metals, unbaked enamel finishes, glass, fiberglass and other plastics. Some decorator tile and colored porcelain is fragile and may be damaged by abrasive cleaning materials. Test a small area before proceeding.