01How the process works
Shot (round) or grit (angular) abrasive is propelled by wheel machines or compressed air at the steel surface. Cleanliness grades Sa 1 to Sa 3 describe the visual result; profile depth is measured by comparator or replica tape.
Residual dust, soluble salts and flash rust between blasting and priming are frequent causes of coating failure. Inspection immediately before coating is a typical hold point.
- Pre-cleaning. Oil, grease and salts removed.
- Blasting. Abrasive cleaning to grade.
- Dust removal. Vacuum or blow down.
- Inspection. Grade, profile, dust, salts.
- Priming. Within the allowed interval.
02What typically goes wrong
| Defect | Typical cause | How it is found |
|---|---|---|
| Insufficient cleanliness | Coverage, abrasive | Visual to ISO 8501-1 |
| Wrong profile | Abrasive size and type | Comparator, replica tape |
| Residual dust | Cleaning | Tape test ISO 8502-3 |
| Soluble salts | Contaminated steel or abrasive | Bresle test |
| Flash rust | Humidity, delay | Visual |
| Embedded abrasive | Abrasive quality | Visual |
03Where an inspector should look
01
Before production
- Grade and profile specified
- Abrasive certificates
02
During production
- Climate
- Abrasive condition
03
After production
- Grade, profile, dust and salt tests before priming
04Standards and references
ISO 8503 (profile), ISO 8502-3 and 8502-6/9 (dust and salts), ISO 11124 and 11126 (abrasives).
Standards are named for orientation. The applicable edition and acceptance criteria are those in your contract and specification.