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Reducing iron content in Electropolishing Bath

I have a electropolishing bath of phosphoric: sulfuric: water in the ratio of 6:3:1 by volume. I do electropolishing os SS304. with a voltage of 9 to 11 volts and temp around 60 to 80 °C. Initially I get good results but after a month the conductivity reduced drastically and I have to change the bath. PLease suggest additive to help settle the sludge or iron content reduction.

RAJIV JAIN
Press shop with electropolishing plant - Aurangabad, Maharashtra, India
2004

Mr Jain,

There are a number of proprietary and generic additives available to chelate the iron. These have side effects like staining, etching and causing pits. However, if long term interests are your concern, you will decant and replace 25% of the bath, on a regular basis .

Regards,

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016
2004

I suggest you add potassium perborate or hydrogen peroxide to the bath. Also the Ph of the bath is to be 5.5 or so. Then the iron will precipitate. In our company we use Hydrogen peroxide.

Anant Chavan
- Mumbai, Maharashtra
2007