ISO/TR 5503:2026

Technical
Report
ISO/TR 5503
First edition
Preparation of steel substrates
2026-09
before application of paints and
related products — Non-visible
residues after surface preparation
with single use abrasives —
Relationship between conductivity
(Bresle) measurements and surface
soluble salt composition on panels
blasted with single-use mineral
abrasives
Préparation des subjectiles d'acier avant application de
peintures et de produits assimilés — Résidus non visibles après
préparation de surface avec des abrasifs à usage unique —
Limites de l'utilisation des mesures de conductivité pour évaluer
la concentration en sel à la surface
Reference number
© ISO 2026
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms and units . 1
4.1 Abbreviated terms .1
4.2 Units .2
5 Supporting data . 2
5.1 General .2
5.2 Sample preparation .2
5.3 Materials .2
6 Results . . 2
7 Conclusion . 5
8 Additional information . 5
Annex A (informative) Methodology . 6
Annex B (informative) Composition of single-use abrasive blasting media used for the tests . 8
Bibliography . 9

iii
Foreword
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This document was prepared by Technical Committee ISO/TC 35, Paint and varnishes, Subcommittee SC 12,
Preparation of steel substrates before application of paints and related products.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv
Introduction
Due to the decreasing availability of slag from coal-fired power plants used as single-use aluminium silicate
abrasive blasting media, other types of single-use abrasive blasting media are being utilized. When inspecting
abrasive blasting work, the salt content is measured using the Bresle test by translating conductivity into
salt content. For abrasive blasting work, it is expected that the chloride content on the abrasive blasted
[9]
surface is low as it increases the lifespan of paint systems (see ISO/TR 15235 and Reference [10]).
When using other single-use abrasive blasting media, salt content is often measured above the maximum
threshold through conductivity, resulting in rejection of the abrasive blasting work. However, the abrasive
blasting media meets the allowed chloride content according to the standard. The remedy is then to rinse
with fresh water and then re-blast without reducing the conductivity.
Conductivity can be caused by multiple salts. Conductivity arises from any water-soluble salts on the
surface and is non-specific. High readings can reflect corrosion-promoting salts or other ions that can be
less aggressive or even inhibitive in solution. However, soluble salt residue can drive moisture uptake and
blistering under coatings.
The Bresle test refers to the test as described in ISO 8502-6 (extraction) and ISO 8502-9 (calculation).
The document is informative and intended to support understanding of Bresle test results rather than to
prescribe testing procedures or acceptance criteria.

v
Technical Report ISO/TR 5503:2026(en)
Preparation of steel substrates before application of paints
and related products — Non-visible residues after surface
preparation with single use abrasives — Relationship
between conductivity (Bresle) measurements and surface
soluble salt composition on panels blasted with single-use
mineral abrasives
1 Scope
This document evaluates the use of the Bresle test (as defined in ISO 8502-9) for assessing soluble salt
contamination on steel surfaces prepared with single-use abrasive blasting media. It presents comparative
data from field and laboratory measurements using different analytical methods to determine whether
conductivity values obtained from the Bresle test can be correlated to chloride and other salt concentrations.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Abbreviated terms and units
4.1 Abbreviated terms
Acc. According
Conc. Concentration
Cond. Conductivity
Corr. Corrected
CSN test Ion detection tube method for Chloride, Sulphate and Nitrate according to ISO 8502-5
1)
and ISO 8502-11
ICP-OES Inductively Coupled Plasma Optical Emission Spectroscopy
ppm parts per million
1) Withdrawn.
UVVIS Ultraviolet–visible spectrophotometry
4.2 Units
µS/cm at 25 °C Unit of conductivity corrected to a temperature of 25 °C
5 Supporting data
5.1 General
Clause 5 provides data to illustrate the possibility of using the Bresle test to support the assessment of
[9]
surface cleanliness from corrosive salts (see ISO/TR 15235 and Reference [10]). The data was obtained
using the methodology described in Annex A.
5.2 Sample preparation
Steel panels were blasted using common single-use abrasives. After blasting, the Bresle test was conducted
at various locations on the panels. The liquid was collected per abrasive used, using glass jars. These liquids
were analysed in a laboratory.
5.3 Materials
— Test panels, steel panels measuring 30 cm × 30 cm × 1 cm, 3 per abrasive blasting media.
— Bresle patches.
— Demineralized water and syringe for Bresle test.
— Glass sample jars.
— Conductivity meter, calibrated and checked immediately
...