The authoritative public forum
  for Metal Finishing since 1989
  

  -----

How many baths to clear the Nitric acid for anodizing

2007

Hi
For the anodizing we use nitric acid bath and for clearing the nitric acid (16 cubic meter water and the nitric acid is 150-200 g/litre) on the aluminium profiles we use cascade baths (4 baths and each bath has 16 cubic meter water) and we put 300 lit. water per hour to the first bath is it enough to clear nitric acid before anodizing or how much water we need to put for an hour for to use 3 baths.

Thanks for your answers from now.

CIHANGIR ÖNÇEKEN aluminium profile producer - Turkey

---

Some communication problems here. By counterflow, I assume that you are a cascade counterflow and that you are putting water into the last rinse tank and not the first tank.
A simple pH test should work just fine. 6-7 would be perfect and you probably can get by with 5. The lower the pH, the more nitric you are taking into the anodizing tank. If you really have 4 cascade counterflow tanks, you are a superior equipped shop and your water use should be minimal UNLESS you are anodizing cupped parts that carry forward a lot of chemical.

James Watts
- Navarre, Florida
2007