A white metal blast cleaned surface is a coating preparation that involves the eradication of all foreign matter which leave a metal gray or even white in appearance.
This surface preparation technique is mainly used where an optimal protective coating performance is required due to severe conditions like continuous immersion in water or liquid chemicals.
White metal blast cleaning is also known as ultimate blast cleaning, sweep blasting or brush blasting.
White metal blast cleaning is a procedure to ensure coating applications will be at their optimum. It involves the removal of all foreign matters such as:
- Rust
- Dirt
- Paint
- Mill scale
- Contaminants
The removal of foreign particles is achieved with the aid of abrasives that are propelled via centrifugal wheels or nozzles. A white metal blast surface is described as a surface with even metallic color, white to gray in color and mildly roughened to produce an appropriate coating anchor pattern.
White metal blast cleaning involves the use of abrasives in conjunction with:
- Water blasting
- Dry blasting
- Vacuum blasting
Performing this type of surface preparation offers benefits such as:
- Maximum adhesion – This surface offers optimal adhesion especially in galvanized steel, aluminum and steel.
- Unlimited recoat time – There is infinite time for recoating so long as the primed area remains grease and dirt free and protected from water exposure.
- Resistance to corrosion – Preparing surface offers outstanding protection against corrosion, especially when used in conjunction with polyurethane coatings.
This process begins by using oil-free air and about 30 mesh sand. In order to perform thorough surface preparation through this method, the following should be performed:
- All surface preparation must be eliminated.
- The operator must stay about two feet away from the area that will undergo blasting.
- The nozzle must be moved at an even rate.
- Bug holes should be released and laitance must be eliminated.
- The surface should be completely dry and clean, and achieve a texture identical to sandpaper in medium grit.
- Loose particles and dust must be eliminated from the area.