The metal’s surface must be thoroughly cleaned after sandblasting to remove traces of dirt, grease, sand, and rust that will interfere with paint. To clean, insert a stiff-bristle brush into soapy water and scrub the entire surface, working top to bottom. Make sure to scrub into crevices to remove grease. Add a corrosion inhibitor to blast water to prevent flash rust.
Rust Prevention After Sandblasting
High humidity areas shorten the 3 hours before rust forms, and painting should occur. Use a clean water source and ensure the substrate is contaminant-free when wet abrasive blasting to prevent flash rust. Properly prepare steel to prevent corrosion. Make sure the surface is kept absolutely dry after blasting to avoid cleaning blast. After blasting, do a chemical clean prior to painting.
Paint Adhesion for Maintained Surfaces
For painted surfaces in sound condition, remove dust then de-gloss and wipe with mineral spirits to aid adhesion. The industry standard is to coat within 4 hours after blasting to avoid re-rusting.