ISO 8501-1 tells you how clean the steel looks. It does not measure soluble salts, roughness, or whether the air is wet enough to condense on the steel. Coating failures after “good blasting” usually sit in those gaps.
- Profile: peak-to-valley depth for mechanical key. BLAST APEX dial gauges cover 0–2000 µm (ASTM D4417).
- Salts: Bresle patch; chlorides under the film cause blistering, especially marine and tank work.
- Dew point: steel must stay a safe margin above dew point. BLAST APEX meters log air, RH and surface temperature.
- DFT: magnetic gauge on ferrous steel after each coat.
- Holidays: high-voltage spark test on thick linings and tank floors.
BLAST APEX sells the five instruments above and also inspects on contract. Quote the spec (Sa 2.5 + profile + ISO 8502 salts + ISO 8502-4 climate) and we kit the job.