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Galvanized Edge Protection G-90 Flat Sheet

2003

I am looking for information on the self healing property of thin gauge galvanized sheets (G-90). We are using flat sheet galvanized material in gauges that vary from 18 to 24 in the production of Architectural metal flashings and trim elements on metal panel buildings. We have some concerns about the prepunched holes in the material rusting at the edges. The manufacturer is stating that the G-90 galvanized coating is self healing across the sheared or punched edge of the material in these gauges.

Are there any technical reports or studies to verify this claim ?

Thank You for your help.

John T. Pickford
- Highland, Indiana

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"Self Healing"? Scratch a piece of galvanized metal and leave it in the rain for a couple of days.

Zinc is a solid metal - how's it going to move across the gap?

Harry Trumble
- Edmonton, Alberta, Canada
May 15, 2009

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I'd agree with Harry that "self healing" doesn't sound like a proper term. Self healing would apply to hexavalent chromium conversion coating, and things like that.

But the galvanizing does offer sacrificial cathodic protection despite scratches or uncoated areas in the same way that a zinc anode protects a steel boat. . I doubt that you'd see much rusting in the area of a scratch on a galvanized component.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
May 15, 2009