Where the
world gathers for metal finishing
Q&As since 1989


-----

Manganese phosphate neutralization

Does Sodium Carbonate or Manganous Carbonate neutralize only the free acid in the phosphate bath? or do they also neutralize the total acid? If they do, is there a rough rate anybody knows about that acid levels do get neutralized?

Also, are there any other substances that might neutralize the free acid such as Sodium Bicarbonate or Carbonic Acid? I don't guess the latter will neutralize anything with it being an acid, but I noticed it in a list of synonyms for sodium carbonate / washing soda [affil links]. Carbonate is a base, right? and Carbonic Acid would be a different form? Confused... Please HELP!

Timothy Hill
Quality Assistant - Mojave, California, USA
2007

---

Currently, we are blasting with 120 grit al. oxide. The metals are AISI 1137 & AISI 3135. I am finding, I think that the core iron parts that we process in this tank easily form crystals, whereas the steels are much more difficult to actually phosphate.

I was somewhat successful after adding potassium permanganate [on eBay or Amazon] and hanging steel wool [on eBay or Amazon] in the bath for an hour at 150 °F. If anyone has ANYTHING to offer on this subject, it would be greatly appreciated. Thanks.

Tim Hill
- Mojave, California, USA
2007