Top blast-cleaning grade for steel (SSPC-SP 5 / NACE No. 1): no rust, mill scale, old paint, oil or shadow staining left anywhere, only an even gray matte. Thermal spray specs call for it under TSA and zinc headed for immersion or severe marine exposure. Near-white (SSPC-SP 10), which tolerates light staining on up to 5 percent of each unit area, is the minimum for atmospheric service.
Inspector failed the sheet piling, near-white won't pass for TSA in the tidal zone, take it back to white metal.
Outside the thermal spray shop, white metal also means babbitt bearing alloy, so a machinist and a blaster can mean very different things by it.
Also heard as
- white metal blast
- SP 5
- NACE 1
Related terms
Grit blasting
Blasting a surface with angular abrasive to clean it and roughen it so the coating can grip.
Anchor profile
The peak-and-valley roughness grit blasting leaves on a surface, which the coating locks onto.
TSA
Thermally sprayed aluminum: arc- or flame-sprayed aluminum that protects steel from corrosion.
Flash rust
A thin rust bloom that forms on freshly blasted steel when it sits in humid air before coating.