Hot dipped galvanized vs. electrogalvanized

Hello, Graeme. Electrogalvanized just means zinc electroplated. Either electroplating or hot dipping can be used to apply the coating of zinc to steel (and there are other methods as well). Zinc electroplating has a definite advantage in appearance and for close fitting parts, but hot dipping will give much better corrosion resistance because the zinc coating will be about five times thicker.

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Hi, Daniel. "Electro galvanized" means zinc electroplated. I don't know the origin of the term but it may have simply been an invention by a marketing manager to attempt to ride the coattails of the more expensive and more durable finish through obfuscation :-)

There should be no compatibility problem between the two finishes but the electroplated parts may not prove very durable in outdoor exposure as the protective zinc coating will only be perhaps a fifth as thick as the hot dipped coating. There is nothing intrinsically questionable about electroplating; it can be an outstanding finish. But zinc electroplating is no substitute for galvanizing in outdoor exposure. Good luck.

Regards,

Hi, James. As long as this plywood is not pressure treated (and it shouldn't be), and as long as the nails are not exposed, I would think that you can let the builder use the nails that he must use for power tools (hot dip galvanized coatings are probably too thick and drippy to use in these machines). But where you have exposed nails, like the top course of shingles at the peak of the roof, you could ask him to hand drive hot dip galvanized nails.

Regards,

Hi, Jacob. Zinc plated materials are invariably chromate conversion coated to deter white rust. Traditionally these chromates were hexavalent chrome based, and hexavalent chrome is yellow-amber in color. Hence the name "yellow zinc". The color could be leached out in hot water, or the coating applied very thin, or trivalent chromate used instead so that it was more clear or more like "white zinc".

Yellow zinc traditionally had much more hexavalent chrome and offered better corrosion resistance. But today there is significant environmental pressure to stop using hexavalent chromates, and in many industries (like the auto industry) only trivalent chromates are used anymore. Some say today's trivalent chromates are the equal of yesteryear's hexavalent chromates.

n the auto industry today the trivalent chromates are simply dyed yellow and are otherwise exactly equal to the "white". Sorry, I don't know whether your yellow roofing material is hexavalent chromated or trivalent chromated and dyed, but that's the short term answer anyway. Eventually there will be no more hexavalent chromium in roofing material and there will be no performance difference between yellow and white. Good luck.

Regards,