plating, anodizing, & finishing Q&As since 1989
Need Help with Plating Polished Nickel over Nickel (Replate)
Need a process to run production numbers of rejected material that has been chrome stripped and then polished so that I can run it nickel over nickel. Everything that I have tried so far is a hit or miss. We have tried different activators and such. I have the adhesion but the plating is not very good with stains and such. Any help with chemicals and a process would be great.William Sklavenitis
You can try following step to plate nickel over nickel.
2 Electroclean -DIRECT current
5 POWER ACID -10% SULFURIC ACID - DIRECT CURRENT
8 WOOD NICKEL STRIKE
10 BRIGHT NICKEL PLATE
TRY IT . GOOD LUCK
Popatbhai B. Patel
electroplating consultant - Roseville, Michigan
Mr. Patel's answer is correct, but the staining will always be a problem with nickel over nickel unless you have perfect cleaning (haha). You could try a barrier layer between the nickels such as acid copper if you have it.
Make sure you have no bare steel showing or the copper will form a non-adherent immersion layer.
Remember to activate and good luck.
electroplater - Galva, Illinois
This is difficult! I have used the following process successfully.
1. Loosen heavy oxide in a mixture of 13 oz/gal potassium permanganate [adv: item on eBay & Amazon] + 13 oz/gal sodium hydroxide for an hour or two at 190 °F. Probably not necessary in your case.
2. Cathodic in a cyanide cleaner, e.g., 2 oz/gal sodium cyanide + 1 oz/gall sodium hydroxide. 2-5 mins.
3. Hydrochloric acid dip. approx. 1 min.
4. Repeat the previous two steps again and again until the surface is easily wetted by water.
(1 oz/gal = 7.5 gms/l)
The problem with nickel that has been used for overplating onto is that it usually contains additives to make it bright. This plays havoc with any subsequent nickel plating adhesion. I would suggest etching the nickel in either a proprietary nickel stripper, cyanide or even using a sulphuric acid/ hydrogen peroxide mix and then using a woods nickel followed by bright nickel.
R&D practical scientist
Chesham, Bucks, UK
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