What is ISO 8502‑9 about?
ISO 8502 discusses the preparation of steel substrates for paint application. ISO 8502 series covers tests for the assessment of surface cleanliness. ISO 8502‑9 specifies a field method for the assessment of the surface density of various water-soluble salts on steel substrates, before and/or after surface preparation, by conductometric determination.
The method described in ISO 8502 assesses only contaminants that form an electrolyte (ions) when in contact with water. These represent the greater part of the contaminants.
Note: The individual surface densities of the salt composition like chlorides, sulphates, sodium, etc, cannot be determined by this method.
Who is ISO 8502‑9 for?
ISO 8502‑9 6 on assessment of surface cleanliness is useful for:
- Paint manufacturers
- Painters
- Builders
Why should you use ISO 8502‑9?
Rusty steel substrates, particularly those of rust grades C or D, even when blast-cleaned might still be contaminated by water-soluble salts and corrosion products. These compounds are almost colourless and are localized at the lowest point of the rust pits. If they are not removed prior to painting, chemical reactions can result in blister formation and accumulations of rust that destroy the adhesion between the substrate and the applied protective coating.
ISO 8502‑9 describes the conductometric method for steel substrates. This is a field assessment for the total amount of water-soluble salts on the steel substrates, the salts being reported as one value. The more aggressive contaminants causing corrosion and blistering (the ionic species) can easily be dissolved off and determined by the conductometric method. This conductometric method described in ISO 8502‑9 ensures that the paint coating on the steel substrate is not affected by water-soluble salts that can cause corrosion and blistering.
What’s changed since the last update?
BS EN ISO 8502‑9:2020 cancels and replaces the first edition (ISO 8502‑9:1998), which has been technically revised. The main changes compared to the previous edition are as follows:
- Inclusion of new measurement methods according to the direct sample method
- Improved connection to ISO 8502-6, and all extraction types
- Dedication to water-soluble salts to avoid confusion with other analysis methods
- Improvement to Figure 1 to clarify the use of other volumes for analysis
