What is Galvanized Metal?
Galvanized metal is made by plating steel with a thin zinc coating. This is done to increase the service life of the steel by preventing corrosion, but it creates some painting problems. What are the problems with painting galvanized metal? One problem concerns the surface treatment manufacturers use to seal off the surface from the atmosphere to prevent (white rusting” during storage. This treatment is often a simple vegetable oil that must be removed before painting or adhesion will be impaired. Solvent cleaning with clean rags (periodically rotated and replaced), washing with a detergent or degreaser, or weathering for several months is usually effective. Weathered galvanized metal will also require cleaning to remove zinc corrosion products. Another problem is the reactivity and alkalinity of the zinc coating. The zinc will react with an oil or alkyd based paint. A saponification reaction will occur causing peeling or softening at the paint/surface interface. What primers should be
As a specially coated type of steel, galvanized metal enjoys a great reputation as being an ideal building product to use for any type of structure that is expected to stand for many years. Here are some basics about how galvanized steel is created, as well as how it can be used in various building projects. Galvanized metal is simply steel in some form that has received a thin coating of zinc oxide. The purpose of the zinc is to protect the steel from elements that normally would lead to oxidation, corrosion and the eventual weakening of the steel. In this sense, the zinc coating acts as what is called a sacrificial anode. In other words, the zinc will protect the steel from corrosion by acting as a barrier between the steel and the corrosive agent, at least until the zinc coating has been completely oxidized. Galvanized metal can be made into supports, girders and even into sheets of metal that can be used in all sorts of construction and building projects. Galvanized metal is often
