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Chromate question

2007

Hi
I am working with a black chromate bath.That composition are 30g/l sodium dichromat
--5 g/l ANHYDROUS sodium sulphate --0.6 g/l of cobalt sulphate -- 0.4 g/l of silver nitrate
and 95 cc/l acetic acid [on eBay or Amazon] and ph is 1.8 -- the immersion time 60-120 sec.
I am coating parts by syanide zinc bath ,but I do not get a correct black film and color is going to brown.
please tell me what I do to get a beter film or give to me a new formula for the make a black chromate bath.
thanks.

Hassan Khalesi
Plating shop employee - Tehran, Iran

2007

Dear Hassan,

Its not worth the time and effort making up your own black chromate bath. But a proprietary two part process and save yourself the cost of rejects instead.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

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