Why is some galvanized material shiny and some dull?
Dark grey of light grey its all galvanized. Protection is equal and often better with dark grey coatings than with light grey coatings. When rimmed or aluminium killed steels are hot dip galvanized, compact zinc-iron alloy layers are formed and covered by zinc, which has a light bluish grey lustre. In some cases the zinc can form randomly oriented crystals to give a spangle finish but this is not a sign of either good or poor hot tip galvanizing, nor does spangle affect the corrosion resistance of the zinc coating. Silicon, which is sometimes added to steel as a deoxidant during its production, speeds up the reaction between the steel and molten zinc. When the steel part is removed from the galvanizing bath but still remains hot, the reaction may continue and convert all or part of the surface zinc layers to zinc-iron alloys. Zinc iron alloys are dark-grey compared with the light grey of zinc and are more abrasion resistant. Usually zinc-iron alloy coatings form more thickly and hence
