Powder Clinic: Powder Versus Galvanizing
Powder Coating or Galvanizing: Which offers the best long-term protection from corrosion?
Q. My question is in regard to the finish that should be used on a cantilever rack that is going to be installed outdoors, uncovered. It is 16 feet high and will be storing building materials that will be loaded using a forklift. The choices are powder coating or galvanizing—which do you think would offer the best long-term protection from corrosion for a Northeast installation?
A. There are many options within the powder coating world for an outdoor system. The surface can be pretreated with zinc, blasted and zinc primed, coated with a fusion bond epoxy (FBE) primer coat, or layered in other ways that will affect the outdoor weathering and abrasion resistance you are going to need in your application.
There are also some very tough thermoplastic coatings that might work well. The best option is probably a layer of FBE and a layer of tough topcoat. The FBE provides a very tough and thick coating with great resistance to moisture penetration. Still, galvanizing might be a better option. It is durable and any areas that are worn from abrasion may show localized corrosion, but it should not spread due to the zinc layer of the galvanizing. Localized areas can be repaired also by application of a cold galvanized spray. The abrasion of the forklift will eventually wear out any coating, so you will want something that is relatively easy to repair.
Originally published in the October 2016 issue.
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