Overview
EN ISO 20567-2:2023 - “Paints and varnishes - Determination of stone‑chip resistance of coatings - Part 2: Single‑impact test with a guided impact body” - is an international/CEN‑endorsed method for evaluating the resistance of automotive finishes and other coatings to stone‑impact damage. Published in 2023 (third edition), this standard defines a reproducible single‑impact test that simulates stone‑chip damage using a wedge‑shaped guided impact body driven by a compressed‑air propelled steel ball.
Key topics and technical requirements
- Scope and purpose: Assessment of stone‑chip resistance of coatings by producing a delamination pattern equivalent to multi‑impact tests.
- Test principle: A wedge‑shaped impact body is pushed into the coating by energy transferred from a compressed‑air accelerated steel ball; loose fragments are removed and the total width of delamination (including the wedge mark) is measured.
- Apparatus: Single‑impact tester with a guided wedge impact body (impact body material: hardened steel, 60–66 HRC). A steel ball (mass less than the impact body) is accelerated by compressed air (nominal 300 kPa / 3 bar).
- Impact body life: The impact body shall be checked and replaced if necessary after a maximum of 500 test runs or at the end of a test series that reaches 500 impacts at the same contact point.
- Test panels: Minimum panel size 100 mm × 100 mm, substrate thickness at least 0.7 mm. Panels must be prepared per ISO 1514 and coated using the manufacturer’s application method.
- Coating thickness: Measured in micrometres by methods in ISO 2808.
- Procedure elements: Calibration, conditioning (refer to ISO 3270 for temperature/humidity), test conditions, number of runs, removal of loose paint, and result evaluation.
- Evaluation & precision: Results are reported as total delamination width; the standard addresses precision (repeatability and reproducibility) and requires calibrated equipment (see normative Annex B).
Applications and users
- Primary users: Automotive manufacturers, OEM paint labs, coating formulators, independent testing laboratories, and quality assurance teams.
- Use cases:
- Comparative performance testing of paints, clearcoats and multi‑layer automotive systems.
- Validation of new formulations or process changes (application, curing).
- Supplier qualification and acceptance testing for stone‑chip resistance claims.
- R&D screening to correlate lab impact behavior with field performance.
- Practical value: Provides a standardized, repeatable method to quantify susceptibility to stone chipping, enabling objective comparisons and quality control.
Related standards
Keywords: stone‑chip resistance, paint testing, single‑impact test, ISO 20567‑2:2023, coatings, automotive finishes, impact tester, wedge impact body.
