Copper is a chemical element with the symbol Cu and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color.

Rochelle salt is used in the cyanide copper plating bath to aid in anode corrosion and tends to give a denser, smoother deposit. Rochelle copper salt is a Acid copper salt.