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Stains after varnishing antique copper

hi everybody
WE DO LOTS OF ANTIQUE COPPER ON ZINC BASE METAL. SCRATCH-BRUSH BEFORE VARNISHING. ON DRYING, THE FINISHED ITEM SHOWS LOTS OF BROWN STAINS. PLEASE NOTE THAT ALL NECESSARY SWILLING PROCEDURE HAS BEEN DONE. THE PLATING IS SODIUM CYANIDE BASE AND ROCHELLE SALT [on eBay or Amazon] . PATINA IS POLYsulfide CONCENTRATE. HELP HELP HELP

ALLY GOOLAMHOSSEN
TECHNICAL supervisor - MAURITIUS
June 28, 2011

Hi, Ally.

Please varnish a couple of components without blackening them, and please allow a couple of plated parts to stand a couple of days with no further post-treatment. I believe that you will see staining and will find that the swilling procedure is inadequate despite your beliefs on the subject. Cyanide bleed-out stains have been a notorious curse on the plating industry for a hundred years so they would always be my first guess on a zinc diecasting.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
June 28, 2011

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