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Brass Zippers: Lacquering Q&A, Problems & Solutions

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Q. Hello, we manufacture sliders for zippers. We do antique silver colour plating on the sliders. First we copper plate on the sliders, on that tin plate, then we do antique silver colour on that. The problem is that if we go to bleach wash or heavy enzyme wash, the colour gets washed off please could you advise us anything?

Habibullah
employer - India
2007

A. Try a lacquer coating over the antiquing.

Michael Berrier
plating shop - Addison, Illinois

A. Any type of silver plating will not stand up to bleach. I've seen chlorine bleach do a real number on sterling silver castings. The only alternative if you have to plate antique silver, is a clearcoat lacquer on top of the final finish. Electrophoretic coatings can also be a good method. Good Luck!

Mark Baker
Process Engineer - Syracuse, New York

Q. Dear sir

Would you kindly recommend suitable washing Lacquer for Zipper.

Regards

Nurul Haque
- Dhaka, Bangladesh
April 5, 2009

A. Hi Nurul,
I'm not totally sure what you mean by 'washing lacquer', but assume you mean a lacquer that is washable? I would re-introduce Mark Baker's idea of electrophoretic lacquer because that technology allows very thin (down to 0.0002") and very uniform coatings which should cause less problems with zipper operation than thicker coatings.
Luck & Regards,

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

Q. Hi to all,

Does anybody have a suggestion of how to increase the resistance of 85/15 Brass zipper teeth when the zipper comes in contact with leatherware.

Gordon Reina
continuous improvement - Varese, Lombardia, Italy
July 28, 2009

A. Hi, Gordon. I'm not sure whether you are implying that leather is corrosive to brass (because of sulfides, tannins, or such), or that brass preservatives may harm the leather? Benzotriazole [on eBay or Amazon (adv.)] sounds like a good bet as a brass preservative, and/or you can apply a clearcoat. Good luck.

Regards,

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

Q. Improving adhesion of lacquer on brass zipper teeth for outdoor application? We are facing corrosion problems (tarnishing) with brass zipper teeth. We have done Scanning Electron Microscopy on some teeth and have seen that we hardly reach 4-5 microns but, what is worse, is that lacquer (PU+acrylic, spray gun) is very unevenly distributed. The images show spots where it seems that lacquer doesn't "wet" the surface.

Greatly appreciate suggestions.

Gordon Reina
Continuous Improvement - Varese, Lombardia, Italy
April 19, 2009

A. Copper or copper alloys can be phosphated or chromated, main application is better paint adhesion. Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia

Goran, thanks for your reply.
Q. Do you have any suggestions about products to use for phosphating or chromating? Are there any safety concerns about Cr6+ ?

We have been using a passivating agent based upon Benzotriazole [on eBay or Amazon (adv.)] prior to coating, which is applied by a barrel turning inside the bath. We did lab tests on passivated Brass strips and the corrosion resistance was excellent. However when we did a production test, with the same parameters, the results were bad. I've read the Benzotriazole layer is very delicate and suffers even slight mechanical damage. What is you opinion ?

Thanks,

Gordon Reina [returning]
- Varese, Lombardia, Italy

A. Chromate process is hex chromate based. I know of only one description of phosphate finish for copper or copper alloys and that is from one ex USSR book. Phosphate finish for brass: HPO4 -2.7 lit, Mn(H2PO4)2-160 gr, NaClO3 -40 gr, water- 4,5 lit, 99 °C temp., 3-5 min -- According to S.J.Grilihes:Oksidirovanie I fosfatirovanie metalov,Leningrad 1971.
Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia

Q. Thanks Goran for your answer.

I couldn't find on the Web the book by S.J.Grilihes which you mentioned. So it is practically impossible to consult it.
Do you have any other literature reference which could be easily found (possibly English or German) concerning the problem ?

Thank you.

Gordon Reina [returning]
- Varese, Lombardia, Italy

A. German handbook on electroplating technology: Handbuch der Galvanotechnik [on eBay, AbeBooks, or Amazon (adv.)] (Dettner,Elze-Hrsg., Muenchen 1968.) - in four books - I am not sure, but you can try to find it. Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia

Lacquer is yellowing

"Zipper: An Exploration in Novelty"
by Robert D. Friedel
zipper

on AbeBooks

or eBay or

Amazon

(affil links)

Q. Hi all,

Have a problem with polyurethane coating which assumes a brown-yellow colour when undergoing a tropical test in contact with leather. Coating protects Brass zipper teeth.

The problem occurs even when coating is put over white carton.

Does anybody have any ideas?

Thanks

Gordon Reina [returning]
Continuous Improvement - Varese, Lombardia, ITALY
January 8, 2010

Q. I've heard our lacquer supplier who said that yellowing might be due to the % of catalyst. Does anybody have any other suggestions?

Your advice is welcomed.

Gordon Reina [returning]
- Varese, Lombardia, Italy

A. Could it be the tannin from the leather? However, it is more likely that the lacquer is not yellowing but the brass substrate is being affected by UV light rays. Try to add some UV absorber to the lacquer if it does not have some already included.

Terry Hickling
Birmingham, United Kingdom

A. You inform me that it yellows (private e-mail) without UV interference. Unless you keep it protected, natural sunlight will yellow some resin systems. Try to purchase a lacquer based on an acrylic resin system ... if I remember I think paraloid acrylic resins dissolved in solvents would be the basis for a suitable varnish.

Terry Hickling
Birmingham, United Kingdom

Dear Terry,

I thank you for your suggestions.
Q. Do you know if any commercial product exists with the properties you mentioned ?

Regards

Gordon Reina
- Varese, Lombardia, Italy

A. Try Paraloid B 44 acryl resin dissolved in toluene (you can use less toxic solvent/or solvent mixture too). 7,5-10% must be ok.I think that Italian company CTS Srl. sells it (conservation of metals is one of its applications). Baked epoxy based clearcoat (special coating for brass/aluminium hardware) can be very good too (Austrian producer is Lorenz Industrielacke, Purkersdorf). Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia
March 17, 2010

PU lacquer gets tarnished by vulcanization

Q. Hello Sir,

I'm working in an accessory garment company which is facing a big problem with lacquering on brass zippers. We are using 2-part PU lacquer to finish our product which be required polished and protection from corrosive. Our customers sewed the brass zippers on shoes then it was vulcanized for 90 mins, 120 °C. Hence the zippers were tarnished.

I'm trying to use another lacquer ( Nitrocellulose ) to solve it but I need some advice which one is suitable with our process to protect the bright brass surface and chemical coating surface (patina, Tin, oxidation coating, etc.)

I greatly appreciate your advice. Thank you!

Son Nguyen
- Ho Chi Minh City, Vietnam
July 6, 2016

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