Unwanted organic contamination is a common problem when using bright nickel plating solutions. To remove contaminants both from outside sources and from brightner breakdown Oxidation treatments are routinely needed. Using potassium permanganate to oxidize and breakdown the organic contaminants so they can be more easily removed on a carbon pack-on filter is a common solution.
Permanganate is a popular choice because it is a much stronger oxidizing agent than hydrogen peroxide and will will remove the more stubborn organic materials.
Unfortunately overuse of the permanganate will cause brittle deposits and roughness. A good way to know you have added just the right amount of permanganate for the amount of organics in the bath is to calculate the amount needed by the following titration:
- Take a 10 ml sample of the nickel bath into a 250 ml flask.
- Dilute to 100 mls with D.I. water.
- Add 5 mls conc. Sulfuric acid
- Titrate with 0.1N Potassium Permanganate to 1st Permanent PURPLE endpoint.
CALCULATION
Mls of 0.1N Potassium Permanganate X 2.4 = Pounds to add to 1000 gallons of nickel solution.
Of course, you should mix this amount in a ratio of 1 lb per 5 gallons and add slowly with agitation over the tank.