[NOL4154]

Dear dfro,
I recommend that you do not copper plate over zinc plating because you are setting up a perfect intermetallic formation zone that in time will become brittle and crack.
I would remove the zinc plating with about 20-30 % muratic acid rinse and quickly plate copper (100-150 micro-inches) because you want to avoid flash rust. You then can follow with nickel and gold.
Give it a try, can not go wrong.
Now, how long to leave in nickel bath, I recommend to refer to Caswell manual because you need surface area information and what type of rectifer you have. Caswell should have a chart for this in your kit.
Nol4154

NOL4154,

Thanks for the information. These zinc plated springs are the only ones I could find that suit my purpose. Maybe if I kept looking I could find a spring this size that is not zinc plated. I will be plating over the zinc first with copper and then plate with nickel and then gold.

I expect the gold layer to wear, but I am hoping that the nickel layer resists oxidation enough to make good enough contact to switch 5 volt logic integrated circuits. I hope the gold keeps the keys I do not play that much from oxidizing. I hope the keys I play more often will keep the nickel plate polished from the slight bit of rubbing.

Maybe I should skip the gold all together and leave a nickel surface finish. What to you think?

Also, how long do you think I should leave the spring in the Plug 'N Plate nickel solution to get a 100-200 micro inch thick plate? The wire thickness is .008 inch and the springs are .063 inch diameter by 1 inch long.

Thanks,
dfro