Tim,
For corrosion resistance the Cadmium is better than Zinc. The yellow finish
on either is a chromate conversion (non electrolytic dip in a chromic acid
solution) and keeps the Cd or Zn from tarnishing. So if you start with a
bright finish (function of the plating process) the chromate will keep it
looking bright and also provide some additional corrosion protection. I
don't think most people could tell the difference between Zn-chromate and
Cd-chromate and the OEM parts were probably Zn. I suspect the Cd plating is
more expensive as it is consider more hazardous by the EPA (reportable
quantity for Cd is 10lbs, for Zn is 1,000lbs. See EPA title III
http://www.epa.gov/ceppo/pubs/title3.pdf ).
Todd Osborn
San Jose, CA
'68 2L DATSFUN
----- Original Message -----
From: "Tim Waltz" <printner@worldnet.att.net>
> I'm not a chemist, nor do I claim to have any knowledge of this area.
>
> I've got a bunch of misc stuff that I want to have re-plated--screws,
> headlight buckets, metal gas tube, etc. I was originally under the
> impression that it should be zinc plated. Some "shiny" zinc, some yellow
> zinc. I've talk to a few platers, and they do cadmium plating in shiny or
> yellow.
>
> What's what? Does anyone know if zinc is better than cadmium or vice
versa?
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