The authoritative public forum
  for Metal Finishing since 1989
-----

Dissolved Oxygen in Type III Sulfuric Acid Anodizing

Q. I hoping someone can explain to me exactly what dissolved oxygen is (in a sulfuric type III anodizing solution) and how to control it. Not exactly sure what other information to ask for. Thank you.

Scott Frazier
- Spokane Valley, Washington
May 12, 2016

---

Q. Thanks Ted. Our line can run 24 hours, seven days a week. We do high production, type III anodizing. When we reach 72 hours of straight running time, we have trouble with cooling and anodize time in the tank. After extended run times (about 72 hours), we do notice an excessive amount of air in the tank. When we take our samples for testing, it takes a few minutes for the air to clear out of the sample jar. I explained this to our chemical rep and he said it's oxygen build up in the solution and it works as an insulator and will slow the anodizing times down. His solution was to reduce the air sparging in the tank or let the tank rest for a few hours.

When we let the system rest, everything goes back to normal. Spoke to another anodizing manager and he has seen the same issue but never knew what it was. I'm open for suggestions and thank for your response Ted,

Scott Frazier [returning]
- Spokane Valley, Washington
May 12, 2016