This guide covers the complete SSPC-SP10 standard: its definition, equivalences with international standards, requirements, verification procedures and the methods available to achieve it.
What Is SSPC-SP10?
SSPC-SP10 is a surface preparation standard published by SSPC: The Society for Protective Coatings (now merged into AMPP — Association for Materials Protection and Performance). It defines a level of cleanliness for steel surfaces prepared by abrasive blast cleaning — or, in current practice, by any equivalent method that achieves the same result.
The standard is formally titled SSPC-SP10 / NACE No. 2 — Near-White Metal Blast Cleaning, a joint standard with NACE International (now also AMPP). Its international equivalent under ISO 8501-1 is Sa 2½.
These three designations are equivalent and interchangeable in coating specifications:
| Standard Body | Designation | Common Name |
|---|---|---|
| SSPC / AMPP (US) | SSPC-SP10 / NACE No. 2 | Near-White Metal Blast |
| ISO (International) | ISO 8501-1 Sa 2½ | Near-White Metal Blast |
| Swedish Standard (legacy) | SIS 05 5900 Sa 2½ | Near-White Metal Blast |
What SSPC-SP10 Requires
The SSPC-SP10 standard defines near-white metal blast cleaning as follows:
When viewed without magnification, the surface shall be free of all visible oil, grease, dust, dirt, mill scale, rust, coating, oxides, corrosion products and other foreign matter, except for staining. Staining shall be limited to no more than 5% of each unit area of surface and may consist of light shadows, slight streaks or minor discolorations caused by stains of rust, stains of mill scale or stains of previously applied coating.
In plain terms: at least 95% of every section of the surface must be completely free of all contaminants. Random light staining of up to 5% per unit area is permitted — this is the only distinction from SSPC-SP5 (white metal), which allows zero staining.
What SSPC-SP10 does NOT define
SSPC-SP10 defines cleanliness — the removal of contaminants. It does not specify an anchor profile (surface roughness). The required anchor profile is determined by the coating manufacturer’s technical data sheet (TDS) for the specific coating system being applied. In practice, most high-performance marine and offshore systems specify between 50 and 100 µm Rz, though some systems (including certain shop primers and surface-tolerant coatings) specify minimums as low as 40 µm Rz. Always consult the specific coating TDS.
SSPC-SP10 in the Hierarchy of Surface Preparation Standards
| SSPC Standard | ISO Equivalent | Cleanliness Level | Typical Application |
|---|---|---|---|
| SSPC-SP5 / NACE No. 1 | Sa 3 | White metal — 100% clean, no staining | Immersion service, thermal spray, aggressive offshore environments |
| SSPC-SP10 / NACE No. 2 | Sa 2½ | Near-white — 95% clean, <5% random staining | High-performance coatings: marine epoxy, zinc silicate, polysiloxane, offshore atmospheric |
| SSPC-SP6 / NACE No. 3 | Sa 2 | Commercial blast — 67% clean | Atmospheric coatings, lower-duty protective systems |
| SSPC-SP7 / NACE No. 4 | Sa 1 | Brush-off blast — loose material removed only | Shop primers, temporary protection |
| SSPC-SP11 | St 3 (approx.) | Power tool — bare metal, 25 µm Rz minimum | Localised spot repair, areas inaccessible to blasting |
How to Verify SSPC-SP10 in the Field
Verification of SSPC-SP10 requires three independent checks. All three must pass. A surface that passes the visual check but fails on profile or contamination does not comply.
Step 1: Visual cleanliness assessment
Compare the prepared surface against the reference photographs in ISO 8501-1 (Sa 2½ panels for the appropriate original rust grade A, B, C or D) or SSPC-VIS 1. Assessment must be done under adequate lighting — minimum 500 lux, natural light or white light preferred. Incandescent warm light is not acceptable.
Identify the original steel rust grade (A = mill scale intact, B = partial rust, C = general rust, D = pitting) and compare against the Sa 2½ panel for that grade. Estimate and record the percentage of any remaining random staining. If staining exceeds 5% of any unit area, the surface does not comply and preparation must continue.
Step 2: Anchor profile measurement
Measure the surface anchor profile using ASTM D4417 Method C — Testex Press-O-Film® replica tape with a calibrated flat-anvil micrometer. This is the universally accepted field method for anchor profile measurement and is specified in virtually all major coating project specifications.
Procedure:
- Select the correct tape grade: X-Coarse (38–115 µm / 1.5–4.5 mil) for most blasted or Bristle Blaster®-prepared surfaces; Coarse (20–64 µm) for lightly prepared surfaces; XX-Coarse (76–178 µm / 3.0–7.0 mil) for aggressive blast profiles and surfaces where X-Coarse reads at its upper limit.
- Apply the tape to the dry, dust-free surface. Press firmly with fingers, then burnish with the rounded applicator included in the Testex kit — minimum 20 strokes in crossed directions.
- Peel the tape and place in the micrometer. Read the total thickness.
- Subtract the tape substrate thickness (50 µm for most tape grades) to obtain the anchor profile in µm Rz.
- Take a minimum of 3 readings per representative area. Calculate the mean. Compare with the coating TDS minimum and maximum profile requirement.
Reference values for the Bristle Blaster® on API 5L pipeline steel: 65–85 µm Rz typical; up to 120 µm Rz measured under controlled test conditions. Results vary by steel grade, condition and tool configuration. The 65–85 µm Rz range is within the profile range specified by most high-performance marine and industrial coating systems — always verify against the specific coating TDS.
Step 3: Soluble salt contamination measurement
SSPC-SP10 does not set a specific chloride limit, but the coating specification or manufacturer’s TDS typically does. The standard field method is the Bresle patch method (ISO 8502-6 extraction + ISO 8502-9 conductimetric measurement). Perform a minimum of two extraction cycles — a single 10-minute extraction underestimates the true salt burden, particularly on profiled steel.
Typical acceptance limits by environment:
- Marine and offshore coatings: <5 µg/cm² total soluble salts (<2 µg/cm² chlorides for demanding offshore systems)
- Pipeline heat-shrink sleeve systems: <3 µg/cm² chlorides (some manufacturers require <1 µg/cm²)
- Standard atmospheric industrial coatings: <20 µg/cm² total soluble salts
If contamination exceeds limits, the surface must be washed with fresh water, allowed to dry, and the full preparation sequence repeated. Re-blasting or re-treating with the Bristle Blaster® after washing is the standard corrective action.
Methods That Achieve SSPC-SP10
Abrasive blast cleaning
The traditional method — and the method referenced in the original SSPC-SP10 standard title. Achieves SP10 reliably on all steel grades and rust conditions when appropriate media, pressure and technique are applied. Requires containment, dust control, abrasive disposal and is prohibited in ATEX Zone 1 environments.
Bristle Blaster® (grit-free power tool)
The Bristle Blaster® achieves surface cleanliness comparable to Sa 2½ (ISO 8501-1) / SSPC-SP 10 through high-velocity wire tip impact without abrasive media. Independently verified for surface cleanliness comparable to SSPC-SP 10 on multiple steel grades and in multiple documented field projects. The pneumatic model carries ATEX certification (Ex II 2G c IIA T4 X) for use in Zone 1 explosive atmospheres — currently the only hand-held power tool with this combination of SP10-comparable capability and ATEX Zone 1 approval.
For the step-by-step procedure for achieving SSPC-SP10 with the Bristle Blaster®, see our guide on how to achieve SSPC-SP10 without sandblasting. For a direct technical comparison with conventional sandblasting, see Bristle Blaster® vs. sandblasting.
Documentation Requirements
A complete SSPC-SP10 inspection record should include:
- Date, time, ambient temperature and dew point at time of preparation and inspection
- Original steel rust grade (ISO 8501-1 Grade A, B, C or D)
- Preparation method and equipment reference
- Cleanliness grade achieved (Sa 2½ confirmed against ISO 8501-1 photographic standard)
- Percentage of any random staining (must be <5%)
- Anchor profile: method (ASTM D4417-C), tape grade used, individual readings, mean value
- Soluble salt result: method, value measured, acceptance limit
- Inspector name and AMPP / FROSIO certification reference if applicable
SSPC-SP10 vs. SSPC-SP11: Understanding the Difference
SSPC-SP11 (Power Tool Cleaning to Bare Metal) is sometimes confused with SP10. The key differences:
| SSPC-SP10 | SSPC-SP11 | |
|---|---|---|
| Preparation method | Abrasive blast or equivalent (e.g. Bristle Blaster®) | Power tool (angle grinder with appropriate accessory) |
| Profile requirement | Defined by coating TDS (typically 50–100 µm Rz) | Minimum 25 µm Rz — no upper limit defined |
| Typical profile achieved | 50–100 µm Rz (blasting); 65–85 µm Rz (Bristle Blaster®) | 25–45 µm Rz — often insufficient for high-performance coatings |
| ATEX compliance | Bristle Blaster® pneumatic: ATEX Zone 1 certified | Angle grinders: not ATEX Zone 1 certified |
| Acceptance for high-performance coatings | Accepted by most major coating manufacturers | Limited — profile typically too low for marine/offshore epoxy systems |
If the specification states SSPC-SP10, an angle grinder with a fibre disc does not comply — even if the surface looks clean. The profile produced by grinding (25–45 µm Rz with directional striations) is materially different from the angular, high-density profile produced by blasting or the Bristle Blaster®.
Frequently Asked Questions
What is the difference between SSPC-SP10 and SSPC-SP5?
SSPC-SP5 (white metal) requires 100% of the surface to be free of all visible contaminants — no staining is permitted. SSPC-SP10 (near-white metal) permits random light staining of up to 5% of each unit area. SSPC-SP5 is specified for immersion service, thermal spray coatings and the most aggressive offshore environments. SSPC-SP10 is the standard for most high-performance atmospheric and splash-zone coating systems.
Does SSPC-SP10 specify a minimum anchor profile?
No. SSPC-SP10 defines cleanliness only. The required anchor profile is defined by the coating manufacturer’s technical data sheet (TDS). For the vast majority of high-performance epoxy, zinc silicate and polysiloxane systems, the TDS specifies between 50 and 100 µm Rz. Always consult the specific TDS for the product and application before defining the preparation protocol.
How do I verify that the Bristle Blaster® achieves surface cleanliness comparable to SSPC-SP 10?
Using exactly the same verification procedure used for abrasive blasting: visual comparison against ISO 8501-1 Sa 2½ reference panels, anchor profile measurement with ASTM D4417 Method C (Testex replica tape), and soluble salt measurement with the Bresle patch method. There is no different procedure for grit-free methods — the surface is evaluated against the same criteria and acceptance limits.
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