Surface preparation standards summary
These are working summaries of the SSPC surface preparation standards a coating inspector references most, written to orient you quickly in the field. They describe what each standard covers, not its acceptance criteria.
The standards themselves, including their photographic references and permitted staining definitions, govern. Always verify the edition your project specification cites.
SSPC-SP 1 · Solvent Cleaning
Removal of visible oil, grease, soil, drawing and cutting compounds, and other soluble contaminants using solvents, emulsions, cleaning compounds, steam, or similar methods. SP 1 is a prerequisite to every other preparation method - blast cleaning over oil drives the contamination into the profile instead of removing it.
SSPC-SP 2 · Hand Tool Cleaning
Removal of loose mill scale, loose rust, loose paint, and other loose detrimental foreign matter with non-powered hand tools such as wire brushes, scrapers, and sanding. Tightly adherent material is permitted to remain, which limits SP 2 to mild service environments and spot repair work.
SSPC-SP 3 · Power Tool Cleaning
The power-tool counterpart of SP 2: removal of loose mill scale, loose rust, loose paint, and other loose detrimental foreign matter with power-assisted tools such as rotary wire brushes, sanders, and grinders. Like SP 2 it allows tightly adherent material to remain and does not require a surface profile.
SSPC-SP 5 / NACE No. 1 · White Metal Blast Cleaning
The most thorough abrasive blast grade: when viewed without magnification, the surface is free of all visible oil, grease, dust, dirt, mill scale, rust, coating, oxides, corrosion products, and other foreign matter. Specified for immersion and the most aggressive service environments where any residual contamination risks premature failure.
SSPC-SP 6 / NACE No. 3 · Commercial Blast Cleaning
Abrasive blast cleaning to a surface free of visible oil, grease, dust, dirt, mill scale, rust, coating, oxides, and corrosion products, except that limited random staining is permitted on a portion of each unit area of surface. A common grade for non-immersion industrial exposure; the permitted staining percentage comes from the standard itself - verify the current edition.
SSPC-SP 7 / NACE No. 4 · Brush-Off Blast Cleaning
The lightest blast grade: removal of loose mill scale, loose rust, and loose coating, while tightly adherent material may remain. Used where service conditions are mild or where the intent is to roughen and clean an existing sound coating rather than remove it.
SSPC-SP 10 / NACE No. 2 · Near-White Metal Blast Cleaning
One step below white metal: the surface is free of all visible contamination except that limited random staining is permitted on a small portion of each unit area. The workhorse grade for high-performance systems such as zinc-rich primers, where near-complete cleanliness is needed without the cost of SP 5.
SSPC-SP 11 · Power Tool Cleaning to Bare Metal
Power-tool cleaning that goes beyond SP 3: the surface is cleaned to bare metal and a minimum surface profile is required, making it a substitute where abrasive blasting is not feasible. Slower and more localized than blasting, so it is typically specified for touch-up, welds, and areas where containment rules out blast work.
Frequently asked questions
What is the difference between SSPC-SP 6 and SP 10?
Both are abrasive blast grades. SP 10 (near-white) permits only limited random staining on a small portion of each unit area of surface, while SP 6 (commercial) permits staining on a larger portion. SP 10 is commonly specified for zinc-rich primers and high-performance systems; verify the exact staining percentages in the current editions.
Does SSPC-SP 1 need to be done before blasting?
Yes, as commonly applied. Solvent cleaning under SP 1 removes oil and grease that abrasive blasting would otherwise drive into the surface profile, so it is treated as a prerequisite to every other preparation grade.
When is SSPC-SP 11 used instead of abrasive blasting?
SP 11 produces bare metal with a required minimum profile using power tools, so it is specified where blasting is not feasible: occupied facilities, small repair areas, welds, and locations where containment or dust rules out blast work.