ISO 22785-6:2026

International
Standard
ISO 22785-6
First edition
Paints and varnishes — Coatings on
2026-06
plastics and composites —
Part 6:
Stone-chip resistance testing
Reference number
© ISO 2026
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test sample characteristics and preparation . 1
4.1 Test samples .1
4.2 Conditioning.2
5 Influence of the plastics substrate on the stone-chip resistance test. 2
6 Overview of test methods . 2
6.1 Test temperature .2
6.2 Stationary multi-impact test .2
6.3 Single-impact test with guided impact body .3
6.4 Single-impact test with a free-flying impact body .4
7 Evaluation . 5
Bibliography . 6

iii
Foreword
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This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee SC 9,
General test methods for paints and varnishes.
A list of all parts in the ISO 22785 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv
Introduction
The ISO 22785 series explains the characteristics of plastics and the differences between plastics substrates
and metallic substrates.
Stone-chip resistance is usually assessed through surface tests; nonetheless, the substrate also has an
influence on the stone-chip resistance of the coating and is considered when testing stone-chip resistance.
Impacts due to loose chippings on a road surface or other materials can cause damage to paint finishes. Such
damage can result in single layers or all layers flaking off from the substrate.
Stone-chip damage can be replicated with single-impact and multi-impact test procedures. ISO 20567-1 and
ISO 20567-4 describe multi-impact test procedures, while ISO 20567-2 and ISO 20567-3 describe single-
impact test procedures.
Many of the existing test procedures for coatings have been developed for metallic substrates, and in the
past they have often also been applied to plastics substrates.

v
International Standard ISO 22785-6:2026(en)
Paints and varnishes — Coatings on plastics and
composites —
Part 6:
Stone-chip resistance testing
1 Scope
This document specifies the testing of the stone-chip resistance testing of coatings on plastics, plastics
composites and similar substrates, hereinafter collectively referred to as plastics.
This document shows the potential effect of plastics on the behaviour of the coating during stone-chip
resistance testing.
2 Normative reference
...