Note: This post is part of a larger series on generic coating types. Click the button at the bottom of this post to download the entire guide.
Zinc coatings are staples of long-term corrosion protection. They are widely used to protect steel substrates in heavily corrosive environments, such as industrial sites and marine settings. These primers are often topcoated with polyurethanes, epoxies or polysiloxanes. Zinc primers prevent steel substrates from coming into contact with oxygen and water, two necessary elements for corrosion to begin to take place. They also act as a source of galvanic corrosion, meaning the zinc primer will corrode preferentially to the steel substrate it protects, essentially sacrificing itself on behalf of the asset. Zinc primers are generally divided into organic and inorganic subcategories.
- Excellent corrosion protection
- Provide two types of corrosion protection
- Inorganic primers provide good abrasion resistance
- Have a tendency to form bubbles or pinholes without proper surface preparation, especially during topcoating
- Usually require topcoats, meaning more associated labor and material costs
- Cannot be applied to a previously painted surface
Zinc primers are typically used on steel structures in corrosive environments. This can include offshore oil platforms, pipelines, storage tanks, power plants, bridges, barge decks and more.
When used in combination with epoxy intermediate coat and a polyurethane topcoat, zinc primers form the base of one of the most proven corrosion-fighting systems currently in use.