Rust, corrosion, and scale remover

A method of removing a corrosion product from a metal surface, said metal being selected from the group consisting of ferrous metal, copper, brass, and bronze, said method comprising contacting said corrosion product with a composition for an effective period of time to remove said corrosion product, said composition consisting essentially of an additive concentrate and water, said additive concentrate consisting essentially of, on a parts by weight basis, 1.5 to 5 parts glycolic acid, 0.2 to 1 parts tetrasodium salt of ethylenediaminetetraacetic acid, 2 to 6 parts citric acid, and 1 to 3 parts trisodium citrate dihydrate, said composition being an aqueous solution, said composition being free from the presence of toxic chemicals listed in the EPA SARA Title III, Sec. 313 toxic chemical list (40 CFR 372.65, Jul. 1, 1993 Ed.).

A method of removing scale from a cooling system which comprises (a) draining any coolant from the cooling system;

• (b) adding to the cooling system a composition consisting essentially of an additive concentrate and water, said additive concentrate consisting essentially of, on a parts by weight basis, 1.5 to 5 parts glycolic acid, 0.2 to 1 parts tetrasodium salt of ethylenediaminetetraacetic acid, 2 to 6 parts citric acid, and 1 to 3 parts trisodium citrate dihydrate, said composition being an aqueous solution, said composition being free from the presence of toxic chemicals listed in the EPA SARA Title III, Sec. 313 toxic chemical list (40 CFR 372.65, Jul. 1, 1993 Ed.);
• (c) circulating said composition through the cooling system for an effective period of time to remove scale from the surfaces of the cooling system;
• and (d) removing from the cooling system the composition and the scale removed from the cooling system surfaces.