What is NACE 2 / SSPC-SP10?
SSPC-SP10 (also known as NACE No. 2) defines a surface preparation grade called « near-white metal blast cleaning ». The standard requires that 95 % of the surface be free of all visible mill scale, rust, coating and contaminant — leaving a uniform grey metal, slightly rough.
This grade is frequently specified for demanding industrial applications. SSPC-SP6 and SSPC-SP3 are not equivalent grades and should be used only when the specification and system documentation permit them.
Anchor profile: follow the specified system
Grit blasting does not just clean: it creates roughness that supports mechanical anchoring. The acceptable range depends on the coating, its film build and the specification. Too little profile can limit adhesion; too much can leave peaks inadequately covered.
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Measure the profile with Testex Replica Tape (coarse or X-coarse grade)
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Define the measurement frequency in the inspection plan
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Document the values in the QA/QC sheet
Choosing the abrasive
The choice of abrasive determines the profile, productivity and dust. Steel grit (G16/G40) offers the best profile for industrial applications — hard, reusable, low dust emission. Garnet (natural mineral) suits sites needing a non-metallic abrasive (food, nuclear). Crushed glass suits delicate surfaces (stainless, aluminium).
The 5 mistakes that ruin adhesion
Even with perfect SSPC-SP10 blasting, certain post-prep mistakes cancel the coating's benefit. Here are the most common ones observed on Canadian industrial sites:
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Time exceeded: applying primer more than 4 h after blasting (flash rust)
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High humidity: blasting at > 85 % relative humidity or surface < 3 °C above dew point
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Dust contamination: not blowing off with clean compressed air before application
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Oily surface: touching the surface with dirty gloves or skipping the second degreasing
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Dirty-solvent degreasing: reapplying contaminants with a used rag
Conclusion
NACE 2 / SSPC-SP10 preparation is not a cosmetic step. Anchor profile, time before coating and ambient conditions must follow the specification and technical data sheet for the system to achieve its documented performance.
Hicham M, P Eng, PMP
Engineer and project manager (PMP) at Induscoat. Over 16 years of experience in industrial coatings, composite repairs and wear protection on mining, energy and petrochemical sites in Canada and internationally.