Why we use NaCN and NaOH

My job is Environmental Engineer and I work for metal plating company I have worked for a year. My department is Quality. Our company have cyanide, acid zinc baths and full automatic Zinc-Phosphate. We use blue ,yellow ,black, green and Cr+3 passivation I want to learn why we use NaCN and NaOH in cyanide baths ?

If you do cyanide zinc plating, you need NaCN and NaOH as essential components of that plating bath. It probably is possible to replace that bath with acid zinc or alkaline non-cyanide zinc, but it involves buying a new process (most likely a proprietary process) rather than just stopping the purchase of NaCN.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Sometimes platers whom use a cyanide based copper strike do because there basis metal corrodes in an acid bath.

Cyanide has been used since the early days of electroplating. Its primary function is to control the concentration (activity) of metal ions. This is essential to control the rate of ionic discharge and hence the quality of the deposit. Sodium hydroxide is present in cyanide processes to maintain alkaline conditions and prevent release of hydrogen cyanide. For a comprehensive discussion I suggest you contact the institute of Metal finishing www.ukfinishing@dialpipex.com . I recently published a paper 'Cyanide in Metal Finishing, Risks and Alternatives' in Transactions which should answer some of your environmental concerns.