Duplex Nickel and Chrome Plating on Stainless Steel

A. We acid etch and Wood's strike our stainless parts. Using the strike is insurance so to speak. You should not be getting roughness out of the strike, though. Keep in mind that a Wood's nickel, like other strikes, is relatively sacrificial and should be made up new relatively often. Are you putting a lot of grit blasted parts through the strike and introducing media to the solution? Also what pore size filters are you using? If they're too large, they're useless.

A. Keep your acid etch. Get rid of the carbon anodes. This is about the worst possible thing that you can put into a Woods strike tank.

Use rolled depolarized cast nickel anodes. McGean Rocho is one of the few companies that still cast them. Bag these and change the bag at least quarterly and every two months would be beneficial. Change your filter elements every couple of days until you do not show any more black stuff on them.

Personal preference is to run the HCl on the middle of the recommended and the nickel on the low end. Optimum adhesion is at 90 -100 ASF, but it falls like a rock at 110ASF, so I would use 80 -90ASF.

This tank system will generate nickel ions, so don't be cheap. Bail some out and replace the volume with an appropriate amount of HCl and water.

You should have absolutely no problem with peeling strike. Strike long enough to see color. That is all it takes.

If you do the above, you should not have any problem with roughness. If you do , increase the flow rate thru your filters rather than going to a finer filter media.

Jim