Metal finishing Q&As since 1989
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Magnigard vs. Empigard Coatings
Q. I am trying to get coating information for external hardware. We use Empigard but it isn't working. The hardware comes in contact with all the elements including marine atmospheres. We are planning to switch to Magnigard.
Any comments? Suggestions? The hardware goes on aluminum housings that are Alodined (yellow chromate) and powder coated. Empigard reacts with the yellow chromate and corrodes very fast. The suggested coating needs to satisfy NEMA-4X requirements for salt spray testing.
Prashant I [last name deleted for privacy by Editor]- Lynchburg, Virginia
A. Hello, Prashant, and welcome to the finishing.com forum. You have mentioned two proprietary products based on a similar technology -- apparently organic topcoats that most commonly go over zinc plating. Comparing proprietary products is a Coke vs. Pepsi / Ford truck vs. Chevy truck type of controversy which we don't address here ... rather, we talk about technologies rather than claims that secret ingredient X is better than secret ingredient Y. But the other steps in the application are a very big part of the equation. I suggest that you talk to a plating shop and resolve a process that meets your product's needs rather than trying to determine from vendors' sales shpeils which proprietary will be most satisfactory. Is the hardware zinc electroplated, or what? Good luck with it!
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Empigard only provides barrier protection. If the coating is scratched the substrate will begin to oxidize. Look into a coating that offers both galvanic and barrier protection such as Magni 565, Geomet+P, Delta MKS. These will greatly enhance the corrosion performance.
Scott BlackPlating/DipSpin/RackSpray/DipDrain/SurfaceEng. - Tampa, Florida, Tampa
September 30, 2013
Thanks Scott. It seems that "Magnigard" is a Magni trade name for a whole line of products rather than a single one. Magnigard Black 23, for example, like Empigard, is a topcoat for electroplated zinc -- so that's the kind of product I was thinking of when I was saying that Empigard and Magnigard are two brands of topcoats usually used for zinc plating.
You are right of course, that Magni 565 and the other brands of dip-spin zinc-rich and/or aluminum-rich coating systems that you suggest will probably outperform zinc plating with a topcoat (if that's what Prashant has!) -- but I am not sure what zinc based coatings, if any, will be acceptable on Prishant's hardware that is used on aluminum housings. Zinc-rich coatings would probably be forbidden in some industries, like aircraft ... so he may be putting the Magniguard onto Ivadizing or aluminum plating rather than zinc plating.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
September 2013
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