plating, anodizing, & finishing Q&As since 1989
Can using Porous Pots Increase Sulfates in Chrome Plating?
June 4, 2010
We have 4 hard chrome plating baths that we have recently been "porous potting" more regularly in the last 2 to 3 months. We do 2 tanks per week as we only have 2 porous pots. The pots are taken out once a day for cleaning/maintenance and replaced in the tank. Not long after, we observed our sulfates steadily rising. In the 3 years I've worked with the solutions, this is the first time I've seen the sulfates rise so fast. Usually, it's a very boring test because we can almost predict what the results would be. (We use the Kocour method to check sulfates.)
Could the porous pots be removing contaminants that may have been binding with the sulfates and now that those contaminants are gone, are we just seeing the "freed" sulfates? (Or is that too weird to even consider?)
We do use tap water for bath make up (always have). We have been monitoring the sulfates in the tap as well. Nothing alarming there. Just normal ranges.
Any ideas what's causing the rise in sulfates?
Plating Engineer - Winnipeg, MB, Canada
- Navarre, Florida
The increased sulfates aren't a result of the porous pot treatment. It must be coming from somewhere else. City water is a likely source as you already know. Even if that is not the source of your current sulfate problem, you should really think about upgrading there. Aside from sulfate, there is probably some chloride in the water that can really throw your bath out of wack. Even if you don't measure much in your City water sample, the problem is that all of those contaminants accumulate in the chrome bath.
Jon Barrows, MSF, EHSSC
Popatbhai B. Patel
electroplating consultant - Roseville, Michigan