Boric acid consumption in nickel plating tank

Since boric acid is not plated out, the concentration should only drop via solution loss. The main form of solution loss is drag-out. A leaking tank can, of course, drop the boric concentration as you fill the tank back up with water, etc. In fact, tracking the boric acid loss is a very useful way to track your drag-out amount, if a person were interested in such knowledge.

Is this a new situation? Is the loss of nickel proportional to the loss of the boric acid? Is the bath level the same? Have you thrown out any solution, like during a filter change or routine PM?

Well, what we thought was the reason for the nickel drop didn't exist. We thought it might be the growth of a nickel tree from a busted anode bag as we saw that in another tank. But there was no growth. There is a small leak in the towers of the tank but we would have to lose a pretty massive amount in order to decrease the nickel and boric enough to need the large adds. I made pretty large nickel sulfamate and boric acid adds yesterday. Today the nickel concentration is up slightly, although not what I would expect after the large add I made. And the boric acid concentration is the same as yesterday, which is to say it's too low. There is not a whole lot of work coming out of the tank so drag out is not really an issue either. Our guys are pretty good about letting the mandrel drain before taking it away from the tank, too. I realize that we are losing some chemistry because of the leak but from my calculation we would have to lose around 13 gallons to account for the nickel drop and 33 gallons to account for the boric drop. Again, I really appreciate the help!

Had some experience with temperature drops that can cause the Boric acid to crystalize out as well.

Thank you for all your help.

We had a new type of anode shipped to us back in June. The supplier said our usual anode was out of stock and they swore this new one was the same as our usual. I almost think that the source of our problems can be traced back to the usage of these anodes. We have been experiencing pitting and pinholes in increased amounts. I sent the new anodes and our usual anodes out for analysis and it showed that the carbon level is 10 times greater in the new ones (0.027% vs 0.002%).  The carbon amount in the new is about twice as much as their C of A states. The sulfur content is about the same at 0.0033% vs 0.0029%.  However, I always thought that the sulfur amount should be closer to 0.0002% for electrolytic anodes. I know they don't have as much sulfur as depolarized anodes but still more than expected in each.  Both types of anodes were soaking in sulfamic acid so I suppose that is where the excess sulfur could come from (?). The new anodes also crush into a black substance much too easily when packed in the cells. This has the anode bags looking very black on the inside of them even though they were just changed within the last month. Could this be from the excess carbon? I also know that if the anodes aren't working correctly that nickel could be drawn out of solution. I've noticed that the pH isn't raising as much from day to day and the surface tension is increasing more often than normal so more wetter has to be added.

I think this may have answered some of Dr. A's questions about product quality, anode bag appearance, and pH. Also, the baskets are full and get packed down often. That is when the operator sees a black cloud coming up from the anode area.

So could that amount of excess carbon be a problem in plating?

Thank you so much for all of your help!