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Imprinting On Chrome Plating

2002

Dear Finishing Experts,

I am looking for some technical information and thought that you might be able to help. Our company silk screen imprints onto various products. Our most challenging product has a chrome-plated stainless steel substrate and the ink we use is a 2 part epoxy type that is recommended for "metals". Despite wiping each unit with isopropyl alcohol before we print on it, we are still having an unacceptable number of failures in the field (i.e. the imprint rubs off when used by the customer).

Questions:
1. I have been told that our decorative chrome surface develops a clear "coating" after plating. Is this true? If so, it may be interfering with the adhesion of our ink to the chrome surface.
2. We may not print a unit right after it is wiped and it may sit for 5-10 days. If the coating was removed when the unit was wiped, will it come back?
3. Will it tend to erode the adhesion of the imprint from below? If so, this may explain why the product looks good to us (passes tape adhesion test) before we ship it but then fails in the field. We purchase this product from Asia fully assembled and plated. We do not have in-house plating expertise. I really hope that you can educate me by answering the above questions of referring me to another technical source.

Thanks!

Brad Shepherd
- St. Petersburg, Florida

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Chrome plating doesn't "wet" so it is difficult to get adhesion of paint onto it. While it does form a chrome oxide "coating", focusing on that fact probably isn't much help because it will be hard to paint whether the painting is attempted immediately or delayed until later.

See "Paint Adhesion over Chromium Plate" by B K Dent, Plating magazine, 1963 vol. 50 pp.1100-1103 and "Studies of Paint Adhesion onto Chromium Surfaces" by K. R. Hasmanis Metal Fin. 1976 vol. 74 pp. 0055-0056.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2002