HDG Hot-Dipped Galvanized Surface Reflectivity

The bright shiny appearance of a newly galvanized coating is sometimes not desired depending on the application. Some government agencies require that the surface of coated steel products not exceed certain reflectivity values. In the early 1970s there were four separate power companies/agencies that demanded galvanized products be dulled, that is, their reflectivity needed to be reduced to a range of 12% to 18% before field installation.

A newly-galvanized part with the normal pure zinc layer on the outside has a natural reflectivity of over 70% in the visible range. If the outer surface of the part has an intermetallic layer, rather than the normal pure zinc layer, the reflectivity is greatly reduced. This reflectivity change will also happen over time as the galvanized part weathers and the zinc oxides and carbonate films form on the surface of the part. However, if the surface must be dulled immediately, there have been some treatments used in the past that have proven successful. If surface reflectivity is an issue, contact your local galvanizer to discuss possible options to producing the desired coating appearance.