In ASTM B117, panels sit in a continuous fog of 5 percent salt solution at 95 F. A scribe is cut to bare metal first, and after the set time, commonly 500 or 1000 hours, the rust creep from the scribe is measured in millimeters along with any blistering. Results compare pretreatments and powders but do not predict field life in years. Specs typically name hours and maximum creep.
Iron phos panels made 500 hours salt spray with 2 millimeter creep, zinc phos went 1000.
Salt spray compares one system with another in the lab; it does not translate into years of outdoor life.
Also heard as
- salt fog
- B117
- salt spray hours
Related terms
Zinc phosphate
A heavy crystalline phosphate conversion coating that gives steel top-tier corrosion resistance under powder.
Seal rinse
A final pretreatment rinse that fills pores in the conversion coating and boosts corrosion resistance.
Pretreatment
The cleaning and chemical conditioning a part gets before powder, which decides most of its adhesion and corrosion life.
Zinc-rich primer
Epoxy powder primer loaded with zinc dust to give steel extra corrosion protection under a topcoat.