TECHNICAL STANDARD
ISO 8502-9
Preparation of steel substrates before application of paints and related products — Tests for the assessment of surface cleanliness — Part 9: Field method for the conductometric determination of water-soluble salts
ISO
2020
Current
WHAT DOES THIS STANDARD COVER?
Describes a field method for the conductometric determination of water-soluble salts on steel surfaces.
WHY IS IT RELEVANT?
Commonly used alongside surface extraction procedures when assessing ionic contamination before coating application.
KEY INSPECTION CONSIDERATIONS
ISO 8502-9 provides a field method for estimating the total amount of water-soluble salts on a surface by conductivity measurement. It is commonly used with surface extracts obtained using the ISO 8502-6 Bresle method. Conductivity reflects the presence of dissolved ionic material in the extraction solution and provides an estimate of overall water-soluble surface contamination. The result should be interpreted against the acceptance requirement specified for the particular project and coating system.
WHAT THE STANDARD SHOULD NOT BE USED TO ASSUME
Conductivity measurement does not identify which individual ionic species are present. A conductivity-derived result should therefore not automatically be described as a chloride concentration unless a chloride-specific analytical method has been used. ISO 8502-9 does not establish one universal acceptable contamination limit for all coating systems. The permissible level depends on the applicable specification, coating system, manufacturer requirements and service environment.
PRACTICAL INSPECTION APPLICATION
ISO 8502-9 is commonly used during inspection of prepared steel before coating application. The inspector should ensure that the extraction and conductivity measurement are carried out using the applicable procedure and that results are recorded for identifiable test locations. Results should then be compared with the acceptance criterion established by the project specification, coating manufacturer or other controlling documentation.
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 8502-9:2020 remains the published edition. ISO currently identifies the standard as "to be revised" and shows ISO/DIS 8502-9 under development as its expected replacement. CMS designation, title and published edition checked against the official ISO record.