The Process: Performance

For over 250 years, hot-dip galvanizing has proven to be a high quality and cost effective corrosion protection coating. In most applications hot-dip galvanizing is superior to paint.

Rust Undercuts Scratched Paint
This is what happens at a scratch on painted steel. The exposed steel corrodes and forms a pocket of rust. Because rust is much more voluminous than steel, the pocket swells. This lifts the paint film from the metal surface to form a blister. Both the corrosion pit and the blister continue to grow.

Zinc Protects Base Steel even when Scratched
This is what happens at a scratch on galvanized steel. The zinc coating sarifices itself slowly by galvanic action to protect the base steel. This sacrificial action continues as long as any zinc remains in the immediate area.

Paint Versus Galvanizing
  Galvanizing Paint
Adhesion Several Kpsi ? - varies
Application Works only on adequately prepared surfaces Inadequate surface preparation can lead to paint failures in field
Availability 365 days a year Depends of weather and humidity conditions
Bond to steel Excellent ? – varies
Cathodic protection Yes No
Curing None required Up to 28 days
Delivery Short turnaround time Can be lengthened by weather delays
Edge protection Equal to protection on other surfaces Thins at edges
Inspection Measurable, Predictable, Reliable, Simple Unreliable, Time consuming, Quality can’t be determined
Maintenance Little, if any Periodic Repairing
Metallurgical Bond Yes No
Photochemically Sensitive No Possible
Prep to Paint Wash Surface Clean Grit Blast to SSPC 6, 8, or 10 and Contain
Transportation Resistant to Abrasion Soft Coating Can Scratch
Tubular Structures Inside and Outside Protection No inside corrosion protection
VOC’s None ? - Varies

There are three basic elements to the galvanizing process:

  1. Surface Preparation (Cleaning)
  2. Galvanizing
  3. Inspection (Quality Control)



Zinc protects the steel in 2 ways. The first is by barrier protection. Zinc provides a tough metallurgical bonded zinc coating, which completely covers the steel and seals it from the environment.