Direct Answer
Shop coating inspection verifies: surface preparation grade (blast profile measured with a replica tape), primer dry film thickness (DFT measured with a magnetic gauge), coverage uniformity, and any holidays (bare spots) requiring touch-up. The inspection is documented with readings per a defined measurement pattern and compared to the project coating specification.
Full Explanation
Surface prep inspection tools: Testex press-o-film replica tape measures blast profile depth (typically 1.5–4.0 mil for most primers). DFT gauges (Elcometer, PosiTector) measure primer thickness on each member — readings must meet both minimum and maximum specified thickness. SSPC-PA1 (Paint Application Standard) defines measurement frequency (one reading per 100 sq ft of surface). Holidays (uncoated areas) are found by visual inspection or holiday detector (spark tester for dielectric coatings). All readings are recorded on a coating inspection report.
What This Means for Your Shop
Coating inspection documentation is part of your project QC record and may be required for owner project close-out. Maintain all DFT readings, surface profile readings, and inspection sign-off records in an organized project file.
Common Mistakes
Applying primer immediately after blasting without verifying the blast profile. A blast that's too light (insufficient anchor profile) results in primer adhesion failure; a blast that's too heavy wastes abrasive and may cause excessive primer consumption.
Recommended Process
After each blast run, measure the surface profile with replica tape before priming. Record results. After priming, measure DFT at specified frequency per SSPC-PA1. Record results. If DFT is below minimum or above maximum, notify the coating applicator for re-application or investigation.