Match your coating system to the right blast profile depth and media type. Based on SSPC-PA 17 and coating manufacturer specs.
Quick answer
Profile depths are typical ranges. Actual results vary with standoff distance, angle, media condition, and substrate hardness. Always verify with a replica tape or depth micrometer.
Required Profile
Too-deep profile causes holidays in thin zinc film
Coal Slag
2.5 to 4 mils
Recycled Glass
2 to 3.5 mils
Crushed Glass
2 to 3.5 mils
Aluminum Oxide
2 to 3.5 mils
Garnet
2.5 to 3.5 mils
Steel Grit
3 to 5 mils
Glass Bead
0.5 to 2 mils
Silicon Carbide
2.5 to 4 mils
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Full cross-reference of all coating systems vs. all media types. Green cells indicate the media achieves the required profile range.
| Coating | Req. (mils) | Crushed | Coal | Garnet | Aluminum | Glass | Steel | Silicon | Walnut | Plastic | Recycled |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Inorganic Zinc (IOZ) | 1.5-3 | 2-3.5 | 2.5-4 | 2.5-3.5 | 2-3.5 | 0.5-2 | 3-5 | 2.5-4 | - | - | 2-3.5 |
| Organic Zinc-Rich | 2-3.5 | 2-3.5 | 2.5-4 | 2.5-3.5 | 2-3.5 | 0.5-2 | 3-5 | 2.5-4 | - | - | 2-3.5 |
| Epoxy Primer | 1.5-3 | 2-3.5 | 2.5-4 | 2.5-3.5 | 2-3.5 | 0.5-2 | 3-5 | 2.5-4 | - | - | 2-3.5 |
| Epoxy Mastic | 2-4 | 2-3.5 | 2.5-4 | 2.5-3.5 | 2-3.5 | 0.5-2 | 3-5 | 2.5-4 | - | - | 2-3.5 |
| High-Build Epoxy | 2.5-4.5 | 2-3.5 | 2.5-4 | 2.5-3.5 | 2-3.5 | - | 3-5 | 2.5-4 | - | - | 2-3.5 |
| Coal Tar Epoxy | 2-4 | 2-3.5 | 2.5-4 | 2.5-3.5 | 2-3.5 | 0.5-2 | 3-5 | 2.5-4 | - | - | 2-3.5 |
| Polyurethane Topcoat | 1-2.5 | 2-3.5 | 2.5-4 | 2.5-3.5 | 2-3.5 | 0.5-2 | - | 2.5-4 | 0-1 | 0-1 | 2-3.5 |
| Alkyd / Oil-Based | 1-2 | 2-3.5 | - | - | 2-3.5 | 0.5-2 | - | - | 0-1 | 0-1 | 2-3.5 |
| Polyurea | 3-5 | 2-3.5 | 2.5-4 | 2.5-3.5 | 2-3.5 | - | 3-5 | 2.5-4 | - | - | 2-3.5 |
| Phenolic | 1.5-3 | 2-3.5 | 2.5-4 | 2.5-3.5 | 2-3.5 | 0.5-2 | 3-5 | 2.5-4 | - | - | 2-3.5 |
| Tank Lining (immersion) | 2-3.5 | 2-3.5 | 2.5-4 | 2.5-3.5 | 2-3.5 | 0.5-2 | 3-5 | 2.5-4 | - | - | 2-3.5 |
| Fireproofing | 3-5 | 2-3.5 | 2.5-4 | 2.5-3.5 | 2-3.5 | - | 3-5 | 2.5-4 | - | - | 2-3.5 |
Green = full match (media range fits within coating requirement). Amber = partial overlap. Dash = no overlap.
Surface profile (also called anchor pattern or anchor profile) is the measurement of peaks and valleys created on a substrate after abrasive blasting. It is measured in mils (thousandths of an inch) using replica tape (ASTM D4417 Method C) or a digital surface profile gauge. The profile provides mechanical adhesion for the coating system by increasing the bonded surface area.
Every coating system has a specified profile range. Too shallow and the coating cannot anchor properly, leading to premature delamination. Too deep and thin-film coatings (especially inorganic zinc) develop holidays at the peaks where film thickness falls below minimum. Getting the profile right is one of the most critical factors in coating longevity.
Four variables determine the profile you achieve: blast media type (angular vs. round, hardness), media size (mesh or grit), blast pressure (PSI at the nozzle), and standoff distance. Angular media like coal slag and steel grit cuts deeper profiles than round media like glass bead. Harder media at higher pressures produce deeper anchor patterns. Standoff distance between 12 and 18 inches is standard for consistent results.
Coating manufacturers publish required surface profile in their Technical Data Sheets (TDS). The specification will list a minimum and maximum profile in mils, plus the required surface cleanliness standard (SP 5, SP 6, SP 10, etc.). Your job is to select a media type and pressure combination that lands within the specified range while also meeting the cleanliness standard.
The most frequent error is over-blasting with coarse media at high pressure when the spec calls for a fine profile. Polyurethane topcoats and alkyd primers only need 1 to 2 mils. Blasting these surfaces with coal slag at 120 PSI produces 3 to 5 mils and forces the applicator to add primer coats to fill the excessive profile. The second most common mistake is using glass bead (which produces 0.5 to 2 mils) when the spec requires 3+ mils for polyurea or fireproofing systems.
SSPC-PA 17 is the industry standard for field measurement of surface profile. It requires a minimum of 10 replica tape measurements per defined inspection area, with the average falling within the specified range. Both the minimum individual reading and the average must meet the coating manufacturer's requirements. Inspectors report the average, minimum, and maximum readings.
Most epoxy primers need 1.5 to 3.0 mils of anchor profile with SP 6 or SP 10 cleanliness. High-build epoxies accept deeper profiles (2.5 to 4.5 mils). Always check the coating manufacturer's technical data sheet for the specific product.
At 100 PSI: coal slag (2.5-4.0 mils), crushed glass (2.0-3.5 mils), garnet (2.5-3.5 mils), and aluminum oxide (2.0-3.5 mils) all achieve 2-3 mil profiles. Coal slag and crushed glass are the most cost-effective options.
Inorganic zinc (IOZ) requires 1.5 to 3.0 mils with SP 5 or SP 10 cleanliness. Too-deep profiles cause holidays because the zinc film is thin. Organic zinc-rich primers are more forgiving at 2.0 to 3.5 mils.
Higher pressure produces deeper profiles. Increasing from 80 PSI to 120 PSI typically adds 1.0 to 1.5 mils of depth. The relationship is not linear. Going from 100 to 120 PSI adds less depth than going from 80 to 100 PSI.
SP 6 (Commercial Blast) removes all visible rust, mill scale, and old coatings but allows light shadows and streaks on up to 33% of the surface. SP 10 (Near-White Blast) allows staining on only 5% of the surface. SP 10 is required for immersion service and high-performance coatings.
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