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Q&As since 1989


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Zinc plated spots

One of my suppliers has zinc plated steel that has zinc falling off, exposing the base metal. The appearance looks like the zinc plated steel has acne. I think that the base is either not being prepared properly or that the plates are not being rinsed correctly. Does anyone know what's happening.

Lawrence Gertig
plating shop - York, Yorkshire, England
2004

Mr Lawrence Gertig,

The plated Zinc was most likely applied to a surface which was not cleaned properly. Or it was rusty. In either case a more thorough Cleaning cycle, or an audit of the current cycle is needed before a final conclusion can lead to remedial measures.

Regards,

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

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I've now been informed that, based on the returned components, the plater now believe that the problem was that there was to much 'brightener' added to the zinc plate process. This resulted in 'embrittlement' of the zinc plate which then led to the 'latent' blistering of the plated surface To a person that has no knowledge of the zinc plating process, this sounds plausible. Could the plater's statement be true?

Lawrence Gertig
optical networking- York, England
2004

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2004

Mr Gertig,

It is entirely possible the plater dumped a lot of brightener in the bath, and this could have resulted in the "Latent Blistering" You should ask your plater, if he is using Alkaline Cyanide-free Zinc, to select the LATEST sixth Generation Alkaline Zinc that does not suffer from these problems. I could name a system that works in the UK, but that will only result in this letter getting blasted off this column! Ensure the plater is well informed by copying him a few leads from this column on suppliers.

Then let him ask the following questions

Is the system tolerant to wide swings in Zinc and caustic.
can it tolerate a Zn as metal range 5.5 to 28 GPL
can it tolerate 85 to 155 gpl caustic
can it tolerate twice the amount of Brightener.And NOT Blister.
can it produce deposits thickness Ratios of 1: 1.15 LCD to HCD.
And can it run at 45 Centigrade. ( Although UK is much cooler ) and whether it can run at 10 centigrade )

If he asks around he will find his answers.

Regards,

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

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Please provide the info to Mr. Gertig in private if you wish, Mr. Nurie.

"I could name a system that works in the UK, but that will only result in this letter getting blasted off this column!"

Exactly. I've yet to see any supplier spend their own money telling people to buy their competitor's product instead. Our supporting advertisers bear the costs of this site, so we can all share camaraderie and technical tips at no cost, but we will not ask them to pay the cost of posting messages that steer the readers towards their competitors.

If a plating shop or supplier wants to promote their products here they should pay their own way. Or if they are truly sincere about just wanting to help for the good of the world and without profit motive, they are welcome to publish their formulation information here instead of holding it as proprietary.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004