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TARNISHING OF ZINC PLATING AFTER HEATING

OUR COMPANY IS MANUFACTURING METAL HOOKS. SOME OF THE HOOKS ARE CHROME PLATED AND SOME ARE ZINC PLATED. IN ZINC PLATED HOOKS WE ARE GETTING SOME PROBLEMS. THE HOOK BEFORE FITTING IN THE PLASTIC HANGERS ARE HEATED AT THE TIP. THIS IS WHERE THE PROBLEM BEGINS THE AREA ABOVE THE HOOKS GET BLACK OR THE PLATING IS TARNISHED IN THE AREA WHICH MAKES THE ZINC PLATED HOOKS UNACCEPTABLE BY THE PARTIES. COULD ANY SUGGEST ME SOME REMEDY ON THIS PROBLEM.

KIRAN PAMKAR
MANUFACTURERS OF METAL HOOKS FOR PLASTIC HANGER - BOMBAY, MAHARASHTRA, INDIA
2003

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2003

Mr. Pamkar,

This may help.

1) Zinc Plate after blue passivation cannot withstand temperatures exceeding 55 centigrade. any higher and the film can degrade.

2) Hanger manufacturers mound the hanger with hook in place, rather than heating the hook and inserting it into a hanger.

3) Another possible reason for black color on heating could be the inclusion of organic impurities in the zinc deposit. It can help to run a carbon filter every 200 hours worked.

4) Hooks are best not heated.

Regards,

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

Dear Mr. Nurie,

In the hangar hook business they use a candle to heat the tip of the hook and twist it into the moulded hangar. Production rates fall once they try moulding the hook along with the hangar.

I suggest a zinc iron black passivation that will not discolor the hook tip on a candle flame.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2003