TECHNICAL STANDARD
ISO 8502-6
Preparation of steel substrates before application of paints and related products — Tests for the assessment of surface cleanliness — Part 6: Extraction of water-soluble contaminants for analysis (Bresle method)
ISO
2020
Current
WHAT DOES THIS STANDARD COVER?
Describes the extraction of water-soluble contaminants from a surface for subsequent analysis using the Bresle method.
WHY IS IT RELEVANT?
Used as part of field assessment of soluble surface contamination before protective coating application.
KEY INSPECTION CONSIDERATIONS
ISO 8502-6 describes the Bresle method for extracting water-soluble contaminants from a surface for subsequent analysis. A defined area of the steel surface is enclosed and contacted with extraction liquid so that soluble contamination can be recovered from the surface. The extraction stage and the subsequent analytical measurement should be distinguished. ISO 8502-6 addresses the extraction procedure, while conductivity determination is commonly undertaken in conjunction with ISO 8502-9. Care should be taken to avoid contamination of the extraction liquid, equipment or test area during sampling.
WHAT THE STANDARD SHOULD NOT BE USED TO ASSUME
The Bresle extraction procedure does not by itself identify individual ionic species present on the surface. When the extracted solution is assessed by conductivity in accordance with ISO 8502-9, the result represents overall water-soluble ionic contamination inferred from conductivity. It should not automatically be reported as a chloride-specific result. There is no single universal soluble-salt acceptance limit applicable to every protective coating system. Acceptance criteria should be established from the project specification, coating manufacturer requirements or other applicable contract documentation.
PRACTICAL INSPECTION APPLICATION
The method is commonly used during surface-preparation inspection before coating application where the project requires assessment of soluble surface contamination. Representative test locations should be selected with consideration of the structure, exposure and areas where contamination may reasonably accumulate. The extraction result should be assessed using the specified analytical method and compared with the project-specific acceptance requirement.
RELATED TECHNICAL STANDARDS
RELATED TECHNICAL TOPICS
Soluble Salt Testing Surface Preparation Contamination Testing
RELATED PIL GUIDANCE
Water-soluble salts can remain on steel even after apparently thorough surface preparation. If they are not identified and adequately controlled before coating application, they can contribute to corrosion, osmotic blistering and premature coating failure.
RELATED EXPERTISE
Inspection Testing & Analysis
ABOUT THIS TECHNICAL SUMMARY
Paint Inspection Ltd provides this information to help inspectors, engineers, asset owners and contractors understand the practical relevance of commonly referenced protective coatings standards. This page is PIL technical guidance and does not reproduce or replace the published standard. Users should refer to the current published standard, project specification, coating manufacturer requirements and other applicable contract documents when establishing project requirements or acceptance criteria.
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OFFICIAL STANDARD
PIL technical summaries are intended to explain the inspection relevance of industry standards and do not replace the published document.
STATUS AND SOURCE VERIFICATION
Official ISO catalogue checked 2026-09-23. ISO 8502-6:2020 remains the published edition. ISO currently identifies the standard as "to be revised" and shows a future revision under development. CMS designation, title and published edition checked against the official ISO record.