Making my own Zinc Anodes?

[cdnpont]

Hello Caswell Forums,

I'm in the process of buying some CopyCad Zinc solution and brightener as I'm hoping to put together my own set-up (3 gallon). I'll be doing mostly fasteners during a automobile restoration. I have a basic power supply, and since I work on a Galvanizing line, I hope to make my own Zinc anodes (have access to 190tons of molten Zinc!). I can also get many different types of acids as well as yellow chromate solution. The nice part is that I would be able to make anodes of any size if needed.

My question is, the zinc I have access to is not absolutely pure.
It contains .125% Al and .030% Fe.

Will the percent of Aluminum and Iron present in the zinc have any real negative effect on plating that you'd know of? Does the Zinc need to be 100% pure?

Cheers, Mark.

[eprigge]

How much impurity you can get away with depends on the particular process Caswell is using. I don't think the aluminum would be a problem but iron causes black spots on parts if it builds up in the bath. Other impurities like copper, lead, cadmium, etc can cause problems too in *very* small quantities. Most metals are more 'noble' than zinc (though not aluminum) so they will be codeposited with it. You'd really have to try it to find out whether there'd be a problem or not.

In the end, it might just be easier to buy anodes you know are good. Standard zinc anodes for acid zinc plating are 99.99% pure. For example:

http://www.palminc.com/metals/zinc.htm

[cdnpont]

Thanks for the reply eprigge,

For all they cost, you're probably right that I should just buy anodes of an known assay, it's a shame with all that metal at my disposal. When I get plating, I'll likely try some "home made" anodes as well, for my own knowledge.

Cheers, Mark.