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Q&As since 1989
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Improving adhesion of lacquer on brass zipper teeth for outdoor application?
"Zipper: An Exploration in Novelty"
by Robert D. Friedel
on
AbeBooks
or
eBay or
Amazon
(affil links)
Q. 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
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
May 22, 2009
May 23, 2009
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]
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
- Varese, Lombardia, Italy
A. Chromate process is hex chromate based.I know for 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!
- Cerovski vrh Croatia
May 27, 2009
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.
- Varese, Lombardia, Italy
May 29, 2009
A. German handbook on electroplating technology -Handbuch der Galvanotechnik [adv: this book on eBay, AbeBooks, or Amazon] (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
June 3, 2009
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