Light orange or brown oxidation that appears on newly blasted steel within minutes to hours, especially when humidity is high or the steel is near the dew point. Spraying over it weakens adhesion and starts undercutting corrosion, so field specs require coating before any visible rust and often a steel temperature at least 3 °C above the dew point. Steel that flash rusts has to be re-blasted.
Humidity's at 85 and we're getting flash rust on the far end, blast smaller sections and shoot each one right away.
Also heard as
- rust bloom
- flash rusting
- turning
Related terms
White metal
The highest blast-cleaning grade for steel: every trace of rust, scale and old coating removed.
Grit blasting
Blasting a surface with angular abrasive to clean it and roughen it so the coating can grip.
Sweep blast
A quick, light blast pass to refresh a prepared surface or clean overspray without cutting deep.