Whisker growth was observed on hot dip galvanised (HDG) zinc and blue chromated bright zinc plate. passivated with blue chrome passivate. For HDG, whisker growth predominated on dull areas, where grain size was small and compressive stresses were present. In electroplating, brighteners produce small crystals and shiny surfaces. SEM analysis showed the presence of chlorine and sulphur. In areas of whisker growth, the chlorine peak was stronger than that of sulphur. Small zinc crystals and surface corrosion by chlorides favour whisker growth. Sulphur is related to filament growth. Although the conditions necessary to produce whiskers are similar on HDG and plated zinc, the filaments themselves differ. On plated zinc, they are smooth and consist of pure zinc. HDG filaments are rough and contain iron and thus are brittle and prone to breakage.
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