Dark spots in nickel and how to lower my ph level in nickel bath

A. Although it is possible to nickel plate with just simple mechanical agitation, most decorative nickel is plated at pretty much a rolling boil of air agitation--so I doubt that too much agitation is the problem. Your pH does seem high, but my first suspicion would actually be iron contamination. Are you using a proprietary process? Have you asked the supplier to analyze your solution? Do you have Hull Cell test capability? Do you have just one nickel tank (Watts bright nickel)? That's a start.

A. You have a huge amount more courage than I do. Going into a business where you do not know how to correct a tank pH is mind boggling to me. I cannot answer the question as you did not say what kind of nickel tank it is. I can guess, but that could be wrong and that would create more grief than you have now. The operating instructions should tell you how to analyze and how to make corrections. If it is a "home brew" solution, refer back to the book that you got the formula from. Why should a competitor or anyone else in the business help you? It will or might possibly take business away from them. Also if you produce substandard products, they can charge more for their quality parts.

A. pH should have 3.8-4.8 is suitable (for bright nickel). If you want to reduce pH, 1 mix sulfuric acid 1 part with cold DI water 5 part 2 if want to reduce pH 5.0 to 4.8 use sulfuric acid 4.4 cc. per 100 liters of solution. If you must to reduce more, you can use this ratio again until it enough.

A. I think we need a bit more information about Mr Peter's process, such as what is the nickel based on (Watts, high chloride, sulphamate, etc.) and whether you are using bright, dull, semi bright, duplex etc. Such details will give a better chance of telling what pH the bath should be. It would also be useful to know temperature and working current densities. I also think Ted could be on the right track; the symptoms of dark spots can be due to impurities.

First of two simultaneous responses --

A. It would be foolhardy to answer your question without knowing the type of nickel bath you are using. We need to know the major components of the bath before any safe answer can be given. The pH is probably too high and can be reduced by adding acid, but which acid will depend on the type of bath. The dark spots are probably due to contamination; have you done a Hull Cell test yet; if so, what was the result? What is the bath used for, this could influence the type of brightener you should add.

Second of two simultaneous responses --

A. A wetting agent lowers the surface tension of the solution so is used in plating as an anti pit material. No, unless you are talking about pits, it will not help brightness unless you have added massively too much will cause a number of other problems.

You add brightener as often as your testing method calls for it. A Hull Cell is a common test mechanism. You have not read the responses to your original post on pH lowering. Simply put, you use the corresponding acid to the anion of your primary source of nickel. This might be hydrochloric acid, or sulfamic acid or sulfuric acid or a couple of others that I doubt you are using.

opinion! The base question here is how did he go into business if he knows nothing about the basics of tank operation? Is he running a properly permitted business, or is he one of the guys trying to "sneak by" the regulators? The obvious source he should be looking to for help would be the company who sold him the equipment/chemistry to set him up in business. If they are reputable they will at least supply him with some documentation which would answer most of these questions.