ISO/TR 5503:2026

• Abstract:

  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.

• Status: Published
• Publication Date: 03-Sep-2026
• ICS: 25.220.10 - Surface preparation
• Technical Committee: ISO/TC 35/SC 12 - Preparation of steel substrates before application of paints and related products
• Drafting Committee: ISO/TC 35/SC 12 - Preparation of steel substrates before application of paints and related products
• Current Stage: 6060 - International Standard published
• Start Date: 04-Sep-2026
• Completion Date: 04-Sep-2026

ISO/TR 5503:2026 is an ISO Technical Report on the relationship between Bresle conductivity measurements and the soluble salt composition left on steel panels blasted with single-use mineral abrasives. It helps engineers, quality managers, inspectors and buyers interpret Bresle results after blast cleaning, especially when conductivity suggests salts but chloride-specific tests do not. The report is informative: it supports understanding of test results rather than setting acceptance criteria or a test procedure.

What does ISO/TR 5503:2026 specify?

ISO/TR 5503:2026 evaluates 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 compares field and laboratory measurements to see whether conductivity from the Bresle test can be linked to chloride and other salt concentrations.

The document is organized into clauses on scope, references, terms, abbreviations, supporting data, results, conclusion and additional information, followed by two informative annexes.

Annex	What it covers
Annex A	Methodology used to generate the reported data, including sample handling, blanks and laboratory analysis
Annex B	Composition of the single-use abrasive blasting media used in the tests

What are the key requirements of ISO/TR 5503:2026?

ISO/TR 5503:2026 is not a prescriptive requirements document. Its main value is the test setup used, the measurements reported, and the conclusion drawn from the data.

• Clause 5 presents supporting data from abrasive-blasted steel panels. In practice, this is the evidence base for judging whether Bresle conductivity can be used as a proxy for specific salts.
• Clause 5.2 and 5.3 describe the samples and materials: steel panels, Bresle patches, demineralized water, conductivity meters and several single-use abrasive blasting media. This matters because the findings apply to that defined test program.
• Clause 6 compares laboratory results from the patch liquid using pH, conductivity, chloride, nitrate and ICP-OES analyses. For a reader, this shows that the report checks conductivity against multiple ion-specific methods rather than relying on one reading alone.
• Clause 7 concludes that low chlorides were found in the abrasive blasting media, while Bresle conductivity suggested chlorides on the surface. The CSN test and liquid analyses did not detect chlorides on the blasted panels, so conductivity cannot always be converted directly into chloride content.
• Clause 8 advises using additional measurements when Bresle conductivity is high. In practice, this means confirming the salt species with methods such as the CSN test, the ION detection tube method, XRF meters, or other ion-specific tests.
• Annex A gives the working method behind the reported data, including blank checks, patch handling and laboratory analysis. This is the part to consult if you want to reproduce the study approach or compare your own measurements.
• Annex B lists the composition of the abrasive media used in the tests. That helps readers relate the results to the type of blasting media, which can affect what is found in the residue.

What terms does ISO/TR 5503:2026 define?

• Bresle test - The extraction-based field test used to collect water-soluble contaminants from a steel surface for later conductivity or chemical analysis.
• single-use abrasive blasting media - Abrasive media used once for blasting, then discarded; the report studies several mineral-based media of this type.
• CSN test - The ion detection tube method for Chloride, Sulphate and Nitrate used as a more ion-specific follow-up test.
• ICP-OES - Inductively Coupled Plasma Optical Emission Spectroscopy, a laboratory method used here to measure dissolved elements in the patch liquid.
• UVVIS - Ultraviolet-visible spectrophotometry, used in the report for laboratory determination of chloride and nitrate.
• µS/cm at 25 °C - The conductivity unit used with temperature correction to 25 °C, which makes field and laboratory readings comparable.

Who uses ISO/TR 5503:2026?

ISO/TR 5503:2026 is used by coating inspectors, corrosion engineers, laboratory analysts, blast-cleaning contractors and quality staff who check steel surface cleanliness before painting. It is also useful for asset owners, specifiers and buyers who need to interpret a high Bresle reading, decide whether further ion-specific testing is needed, or compare abrasive media performance in practice.

Which standards are used with ISO/TR 5503:2026?

• ISO 8502-6 - Defines the Bresle extraction method used to collect water-soluble contaminants.
• ISO 8502-9 - Defines the field conductometric determination of water-soluble salts and is the Bresle test basis cited by the report.
• ISO 8502-5 - Provides the chloride ion detection tube method named in the document.
• ISO 8502-11 - Provides the turbidimetric field method for water-soluble sulphate.
• ISO 11126 (all parts) - Gives specifications for non-metallic blast-cleaning abrasives, which the report uses when discussing abrasive media limits.
• ISO 11127-6 - Gives the conductivity test method for non-metallic blast-cleaning abrasives.
• ISO 11127-7 - Gives the chloride test method for non-metallic blast-cleaning abrasives.
• ISO/TR 15235 - Provides collected information on the effect of water-soluble salt contamination on coating performance.

What does the ISO/TR 5503:2026 document contain?

The document contains a short technical report with supporting data, a results section and a conclusion based on field and laboratory measurements. It includes a table of the abrasive blasting media used, a table of laboratory results from the patch liquid, and an overview table comparing Bresle conductivity with chloride and other analyses.

Annex A sets out the detailed procedure used to prepare panels, make blanks, collect patch liquid and send samples for laboratory testing. Annex B lists the composition of the abrasive media used in the reported tests.

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
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
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
...