ISO 22785-6:2026

ISO 22785-6:2026 is an International Standard from ISO for testing the stone-chip resistance of coatings on plastics, plastics composites and similar substrates. It explains how the substrate can influence coating behaviour during stone-chip resistance testing, so laboratories and product teams can judge results on plastics in a controlled way.

What does ISO 22785-6:2026 specify?

ISO 22785-6:2026 specifies stone-chip resistance testing for coatings on plastics, plastics composites and similar substrates, which the document treats collectively as plastics. It organizes the subject into sample preparation, the influence of the plastics substrate, an overview of test methods, and evaluation.

The document is structured in Clauses 1 to 7, followed by a bibliography. In practice, that means the user can move from specimen preparation to test selection and then to result interpretation in one place.

What are the key requirements of ISO 22785-6:2026?

ISO 22785-6:2026 focuses on how to prepare samples, how to condition them, which test temperatures to use, and how to evaluate damage. The main point is that plastics behave differently from metal, so the standard makes substrate effects part of the test interpretation.

• Test samples and geometry - Clause 4.1 covers coatings on standard test panels specified in ISO 1514 and on components. Flat panels are usually used, but other specimen geometries have to be agreed between the interested parties and stated in the test report. In practice, this means the test setup must match the part being assessed and the report must record any non-standard shape.

• Surface preparation and film thickness - Clause 4.1 says the coating system, substrate, pre-treatment and coating method are selected together to achieve a homogeneous coating, and cleaning substances must not change the material properties of the panel. Film thickness is documented according to the technical requirements for appearance, coating, or both. This matters because the condition of the sample can change the stone-chip result.

• Conditioning - Clause 4.2 says conditioning is used to improve repeatability and reproducibility, and that plastics often need longer conditioning than metals because humidity affects them more strongly. Unless otherwise specified, the test samples are conditioned for 16 h under the standard climatic conditions in ISO 3270. In practice, the conditioning step is part of making results comparable.

• Substrate influence - Clause 5 explains that hardness and flexibility depend on temperature and can influence the stone-chip test result. Results from flexible plastics substrates and hard plastics substrates are not comparable. This is important when comparing coatings across different plastic types or across different use temperatures.

• Test temperature - Clause 6.1 says tests should be carried out at temperatures where the substrate is in the same form of appearance as in use. The note says room temperature is typically 18 °C to 28 °C. For users, this means the test should reflect the service condition rather than only a laboratory default.

• Stationary multi-impact test - Clause 6.2 refers to ISO 20567-1. The coating is hit by many small, sharp-edged impact bodies, using specified iron grit and compressed air. Damage is judged by comparison with reference pictures after loose fragments are removed. The test area is 8 cm × 8 cm. This method suits screening and visual comparison of damage severity.

• Single-impact tests - Clause 6.3 refers to ISO 20567-2, using a guided impact body with a wedge-shaped blade and a steel ball accelerated by compressed air. Clause 6.4 refers to ISO 20567-3, using a free-flying impact body where angle, speed, mass and geometry are specified. The first measures detached width including the imprint; the second records damaged area, and for multilayer systems the main separation planes. These methods are used when a single, defined impact is needed.

• Evaluation - Clause 7 says the surface is evaluated as described in the relevant test standards, and that colour or transparency can make visual assessment harder. For release tests, a high-contrast colour layer is selected, and wetting the samples with water can improve contrast on plastics. That helps the examiner see chip damage more clearly.

What terms does ISO 22785-6:2026 define?

ISO 22785-6:2026 uses the terms and definitions from ISO 4618 and ISO 22785-1. Key terms in the document include:

• Plastics - The collective term used here for plastics, plastics composites and similar substrates.
• Coating system - The coating, substrate and pre-treatment considered together when preparing test samples.
• Test panel - The standard flat specimen used for many of the tests.
• Conditioning - The controlled exposure used before testing to stabilize the sample.
• Stationary multi-impact test - A repeated-impact method that uses iron grit and compressed air.
• Single-impact test with guided impact body - A one-hit method that uses a guided wedge-shaped impact body.
• Single-impact test with a free-flying impact body - A one-hit method where the impact body is launched toward the sample.

Who uses ISO 22785-6:2026?

ISO 22785-6:2026 is used by paint and varnish laboratories, coating developers, plastics and composites manufacturers, and quality managers who need to assess stone-chip resistance on plastic-based parts. It is also relevant to buyers and technical teams that compare coating performance on plastic substrates and need a common test approach for reporting and agreement.

Which standards are used with ISO 22785-6:2026?

ISO 22785-6:2026 refers to ISO 4618 for vocabulary and ISO 22785-1 for the general introduction to coatings on plastics and composites. Its bibliography also names ISO 1514 for standard panels, ISO 3270 for conditioning and testing climates, and ISO 20567-1, ISO 20567-2, ISO 20567-3 and ISO 20567-4 for the stone-chip test methods it points to.

What does the ISO 22785-6:2026 document contain?

ISO 22785-6:2026 contains sample preparation guidance, conditioning guidance, an explanation of how plastics substrates affect test results, and an overview of the main stone-chip test methods. It also gives practical evaluation guidance for visual assessment and describes how contrast can be improved for plastics.

Figures 1 to 3 show example test devices for the stationary multi-impact test, the guided single-impact test, and the free-flying single-impact test. Those figures help laboratories understand the type of equipment and arrangement the methods refer to without reproducing the full test procedures.