pickling brass

[unclesalty]

I am trying to reduce the time it takes to pickle brass using sulfuric acid. In the process brass pieces are tumbled in large wash drums containing sulfuric acid. Would it speed up the process if I increased the concentration of sulfuric acid (it's currently about 5%). Also, would adding hydrogen peroxide help?
Thanks,
Ernie

 

[TVP]

Increasing the concentration to 15-20% would increase the removal rate, and is still within acceptable practice. It is recommended to add 3-5% hydrogen peroxide (composition = 35%), with the balance being water. Temperature can be RT up to 60 C, with increasing temperature increasing reaction rate. Immersion time varies from ~ 15 seconds to ~ 5 minutes. I highly recommend ASM HANDBOOK Volume 5 Surface Engineering as an excellent reference related to coatings, cleaning of alloys, etc.