Specifications shout about cleanliness, Sa 2.5 in every second line, and whisper about profile, yet adhesion lives in the profile: the microscopic peaks and valleys the coating keys into. Get the anchor pattern wrong and a perfectly clean blast still delaminates.
What the numbers mean
Profile is measured as peak to valley height in microns, by replica tape or stylus gauge. Typical high build epoxy systems ask for 50 to 85 microns; thin film systems want less, heavy glass flake and thick linings want the upper range. The coating data sheet states its window, and both directions of error cost: too shallow starves adhesion, too deep leaves rogue peaks poking through the film as future rust spots.
Abrasive drives the pattern
Angular abrasives, copper slag, garnet, crushed grit, cut angular profiles that coatings grip; rounded shot peens a shallow pattern suited to different processes. Size sets depth: coarser grades dig deeper profiles, finer grades polish shallower ones, which is why grit selection follows the coating, not the compressor. A 30 by 60 mesh garnet sits comfortably in the mainstream epoxy window, one reason it is the yard staple.
Practical control on site
Measure profile at the start of each blast day and when abrasive lots change, keep replica tape readings with the DFT records, and watch recycled abrasive: each pass through the machine rounds and breaks it down, drifting the profile shallower until screening and topping up restores the working mix.
MENA Industrial Supplies stocks abrasives matched to specified profiles and the coatings they anchor, quoted same day from Dubai across the UAE.