Zinc Diecasting Cleaning Solution
A cleaning solution is available for brightening diecastings that have become tarnished during storage. It has the following composition:
Syrupy phosphoric acid (Sp.Gr.1.75) 60 parts by weight
Butyl alcohol (or another suitable miscible organic solvent) 20 parts by weight
Water 20 parts by weight
Wetting agent 2 parts by weight
This solution should be stored in a non-metallic vessel. The diecastings should be degreased if necessary and then immersed in the solution at room temperature for 10-20 seconds. After treatment the castings should be well rinsed and dried. They are left with a faint iridescence.