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Zinc plating beginner asks how to connect rectifier

Hello, I'm a beginner in Zinc plating.. now I'm running a company in venezuela which makes small metalforming pieces and zinc plating them. The baths composition are Zn:Cyanide:NAOH 1:2.7:1.8. The tanks are of steel. I need information to learn all the secrets of this process if anyone of you can send me anything I will appreciate it.

I have a cyanide zinc baths on a steel tank, the positive lead of the rectifier is conected to the tank and the anodes are hanging in chests from a steel bar welded to the tank... the negative lead are conected commonly to the pieces to be plated. I don't now if that is correct because the theory sais to conect the anodes to the rectifier and insulate from the tank... we have problems with the process and any information could help.. thanks!

The question is: the anode is connected to the rectifier thru the tank in means the current goes tru the tank to the bath... I don't now if that is correct or not because the theory says to connect directly to the zinc anodes and insulate from the tank... ?

Eduardo González
plating shop employee - Charallave, Miranda, Venezuela
July 17, 2008

July 19, 2008

Hi, Eduardo. Both sides of the rectifier should be insulated from the tank. The anode rods should not be welded to the tank. You should try to get a few plating books to help you with the secrets of the process. Good luck.

Regards,

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

Eduardo,
The current travels through the liquid, not the tank. The tank is there only to contain the liquid. As a matter of fact, there are tanks made of non conductive materials like plastic, glass fiber, etc. The current flows from the anode baskets (+) to the part (-). Listen to Ted's advise, get a book about the subject. Plating involves numerous dangers that can go from damage to valuable parts and equipment to their destruction, risk of explosion, fire, cronic illness and even death from exposure to potent venoms. Buena suerte!

Guillermo Marrufo
Monterrey, NL, Mexico
July 21, 2008

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