Abrasive Blasting Basics
Good blasting comes down to control. Keep steady air pressure (commonly around 90 to 100 psi at the nozzle for most work), hold the nozzle roughly 12 to 18 inches from the surface, and angle it about 60 to 90 degrees to the work. Keep the nozzle moving in consistent passes to avoid gouging and to leave an even result.
Blast Media
Choose media based on the substrate, the coating you will apply, and the profile you need. Coarser media such as steel grit or coal slag cut faster and create a deeper profile, while finer media leave a smoother finish. Make sure the media is clean and dry before use.
Cleanliness Standards
Surface cleanliness is measured against industry grades such as the SSPC and NACE standards, for example White Metal, Near-White, Commercial, and Brush-Off blast. The coating spec states the grade required, so prepare and inspect the surface to meet it before coating.
Surface Profiling
The surface profile (anchor pattern) is the depth of the texture left after blasting. Measure it with a profile gauge, replica tape read with a micrometer, or a depth micrometer, and confirm it falls within the range the coating manufacturer requires for good adhesion.