Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Painting of zinc plated parts
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Q. In order to get 800 hrs salt spray resistance we apply zinc plating, clear passivation, and black powder coating on steel sheet. The problem is on some products we cannot achieve sticking of paint. Thank you for your interest. Sincerely
Mehmet Yazici- Istanbul, Turkey
2000
A. I would recommend eliminating the clear passivate (chromate?) step and pretreat the parts with an organically accelerated iron phosphate. I believe you are damaging the chromate with the required cure temp of the powder coat.
Dan Brewerchemical process supplier - Gurnee, Illinois
RFQ: Hello everyone,
I recently discovered this site and thought I might post a message in the hope someone may be able to assist.
I have a large quantity of zinc-plated Meccano (two Set No. 10s and the equivalent of a third) that needs professional replating. A No. 10 comes in a four drawer wooden cabinet and a significant proportion of its parts are zinc-plated, so this might be in the order of a small industrial job.
I'm trying to find an Australian zinc-plating shop, ideally based in NSW, that would be able to carry out this job to a high standard. The Parts range in size from the very small (such as nuts, bolts, washers etc.) to the very large (such as 24.5" angle girders etc.)
All parts could probably be done by barrel rather than rack but I would be open to professional advice. The finish I'm after is "factory" bright zinc without further processing.
Thank you
Cameron P NSW, Australia2001
Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)
Q. I have a selection of angle girders perforated strips and plates (meccano parts} that are zinc plated. I want to paint these items with red and green from a spray can and then bake them in an oven to harden. I would like to know how to remove the zinc plating so that I go back to the bare metal or whether it is possible to just spray over the zinc plating.
Brian Henley- Auckland, New Zealand
2001
Q. I have the same problem as Cameron P & Brian H. I have zinc plated Meccano parts from 1972 and would like to refinish these in an authentic but non corroding manner. Ideally, I would like to find out how to strip off the zinc and re-plate with nickel or, otherwise, to just re-do the zinc. I don't have access to any of the follow-ups they received but would appreciate knowing what they were able to find out.
Best regards,
Richard Leveson- Toronto, Ontario, Canada
2002
Epoxy Paint doesn't adhere to Acid Zinc Plating
Q. Hi,
We cannot paint(with epoxy paint)the steel pieces which are plated acid zinc.
How can we do that ?
Many Thanks,
plating shop employee - Istanbul, Turkey
December 1, 2009
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A. Acid zinc may have too much organics in it to plate well. To my weak knowledge on painting, all zinc should have a special primer for zinc. It used to be zinc chromate but that has largely been replaced by an acid wash primer. James Watts- Navarre, Florida A. All zinc coatings cannot be painted without either 1) a paint designed especially for this substrate, or 2) a primer or pretreatment system designed to pretreat zinc for subsequent top coats.  Geoff Crowley Crithwood Ltd. Westfield, Scotland, UK  |
Q. Sir, I am working in Haier Pakistan. We are facing paint problem in our refrigerators door which are Electroplated Zinc. Sir, I need to know what are the reasons of paint removal?
Also please tell me if hydraulic oil used during processing has anything to do with this problem
Haier Pakistan - Lahore , Pakistan
January 21, 2018
A. In addition to the previous answers, check if the parts have been passivated.
Ronald ZeemanCoil Coating - Brampton, Ontario, Canada
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