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There are several ways to apply zinc to steel but none offers the protection of HDG:
• Metallizing is an expensive process in which zinc in wire or powder form is sprayed onto the steel. Because the zinc is sprayed onto the steel instead of migrating into the steel like HDG it only provides barrier and limited cathodic protection.
• Zinc-rich Paint is a paint that contains up to 78% zinc by weight and is one of the approved repair methods for HDG in ASTM A780, the repair specification for HDG. However, as with most paint coatings, the quality of the application is a major factor in determining the long-term performance of the coating. Consideration must be given to the initial steel surface condition (is it new, rusty or contaminated?), proper surface preparation, weather conditions (properly controlled temperature and humidity), the skill of the painter, the curing process and handling.
• Continuous Galvanizing is typically used for very thin sheet products. Coils of steel sheet metal are fed as ribbon through a molten metal bath where it reacts to leave a protective surface coating. It has similar properties to hot-dip galvanizing, but the coating is thin since one of the factors affecting how much zinc will bond to the steel is the thickness.
• Electroplate Galvanizing is the process whereby zinc is electrochemically applied to the steel. The coating thickness is very thin.
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