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Brightening electroless gold plating: replace sulfuric acid without fuming

Dear Sir,

I am in jewelry manufacturing.We make a gold plating solution by using common salt, sodium nitrate ⇦this on Amazon [affil link] , sulfuric acid, water and heat this solution with pure 24 carat gold, which gets dissolved in this solution.

Then once our jewelry is finished we heat this solution and put our articles in it and heat it and then stir it with a copper wire which aids the gold in the solution to deposit onto the articles, but with a blackish tinge. We then put these colored articles in boiling hot sulfuric acid and the blackish tinge is gone leaving a bright gold yellow 24 carat color.

I need some chemical which can clear this black tinge and give me an equally bright yellow (24 carat Looking) color without the fuming instead of the sulfuric acid. It has to be a chemical as we do not have space to put a scrubber unit.

Kartik Jhaveri
plating- Mumbai, Maharashtra, India
2005

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A. Karthik

There are options open for you to consider.

1) Install a gold flash fumeless plating unit and depart from the age old Traditional " Sone ka Paani chadane vale system "

2)Use a cyanide dip which contains potassium cyanide which can also cause death in seconds ! I would not recommend this one at all.

You have limited options of using a warm dilute 10 % sulfuric dip and adding Hydrogen peroxide to de oxidise the black finish. This too gives off fumes.

Try a Dry acid salt at 250 grams per liter with 5% sulfuric acid at 40 °C. It may not fume. It may or may not give the bright finish.

However a Flash plating unit is what will get you production and good health.And a one step plated Bright finish. Long life to you and the finish..even small guarantee for life of finish.

Regards,

Asif Nurie [deceased] [deceased]
- New Delhi, India
With deep sadness we acknowledge the passing of Asif on Jan 24, 2016