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Stripping Nickel From Invar

adv.

Q. We strip nickel plating from Invar using a cyanide based solution and for the most part have success, however, from time to time have catastrophic results where the parts are etched and attacked. Despite concentration checks, electrically isolating parts and tank sidewalls, etc., we're never able to recreate the etching (and other non-Invar parts in tank at same time are fine). Any thoughts on what might be going on? While I'm convinced that there is a good bit of science behind what we do, part of me holds out that there is still a blend of witchcraft, voodoo and alchemy involved.

Milt Stevenson, Jr.
Syracuse, New York
February 7, 2022