Chloride Concentration in Watts Nickel

Question:

For reasons too lengthy to discuss in this question, one of our Watts nickel plating baths has a very high chloride ion concentration. The concentration range is approximately 18–19 oz/gal. This bath is set up as a semi-bright bath. How can the excess chloride be removed from the bath? I prefer not to go the dilution route. F. K.

Answer:

Yes, your bath is rather high in chlorides but you still should be able to obtain satisfactory deposits. You do not mention anything in your question regarding stress levels but if this is an issue for you, reduce the level of chloride in the bath. The usual recommended concentration for nickel chloride is around 10 oz/gal. If you feel that the excess chloride should be removed, you can use a soluble silver salt. Obviously you must first perform some lab work to determine the amount of silver salt required to remove a given amount of the chloride. The chloride will precipitate out of the solution as silver chloride. The precipitate must be carefully filtered from the plating solution. This step is critical otherwise you will have rough nickel deposits once you start plating in the tank. The precipitation and filtration should not be performed in the plating tank.