How it works
Steel grit particles have sharp edges. On impact, they cut and fracture mill scale, rust and old coatings and leave an angular, jagged profile that coatings can anchor to. Grit is supplied in several sizes and hardness levels. Larger, harder grit cuts deeper; finer grit gives a lower profile and a cleaner appearance. The working mix in a recycling system, made of new and partly worn particles, determines the profile actually obtained.
Steel grit and steel shot
| Feature | Steel grit | Steel shot |
|---|---|---|
| Particle shape | Angular | Round |
| Surface effect | Cuts an angular profile | Peens and hammers the surface |
| Typical use | Coating preparation, scale and rust removal | Peening, cleaning of castings, some descaling |
| Common combination | Mixed with shot in some wheel blast systems | Mixed with grit to balance cleaning and profile |
Coating specifications generally require an angular profile, which is why grit or a grit-rich mix is used for coating work.
Where it is used
- blast rooms and blast cabinets with abrasive recovery;
- wheel blast machines for beams, plates and fabricated parts;
- field projects with vacuum or recycling equipment, where containment and recovery are already in place;
- preparation for metallizing and immersion linings that require an angular profile and a high cleanliness grade.
Open field blasting without recovery normally uses expendable mineral or slag abrasives, such as garnet, because collecting steel grit is impractical there.
Quality and maintenance
- Cleanliness. Recycled grit must be kept free of dust, fines, oil and soluble contamination. A conductivity test of the abrasive is commonly used to check for soluble salts.
- Operating mix. Fresh abrasive is added regularly to keep the size distribution and profile stable.
- Moisture. Wet grit rusts and clumps; storage and air supply must be kept dry.
- Standards. SSPC-AB 3 covers ferrous metallic abrasives and SSPC-AB 2 the cleanliness of recycled ones. ISO 11124 sets specifications for metallic blast-cleaning abrasives, and ISO 11125 the test methods.
The profile obtained is checked per ASTM D4417 against the coating data sheet. Abrasive choice is part of every plan in our abrasive blasting service.