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Ask the Expert Question-and-Answer Archive

by Ron Joseph

February, 2005

Zinc Chromate Primer vs. Red Oxide Primer

Q. For iron surfaces used as support work (e.g. angle iron for duct and pipe hangers) which one is a better primer, zinc chromate or red oxide?

A. Thank you for your email. Zinc chromate and red oxide are two pigments that are commonly used in metal primers. Zinc chromate provides more corrosion resistance than red oxide, although red oxide is excellent for exposure to sunlight and exterior exposure.

If you are concerned about corrosion, then in my opinion, zinc chromate will give you better corrosion resistance. Bear in mind that I haven't seen your structural steel, I don't know the condition of the metal substrate, I don't know in which country the steel is located or the weather conditions that you experience. Surface preparation before painting is also critical in making a decision. It is possible that other primers might be more appropriate than either zinc chromate or red oxide, but without having much more information, I can't be more specific.

I hope this help.

Best wishes,

Ron Joseph

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