The standard "EN ISO 20567 Paints and varnishes - Determination of the resistance of coatings to stone chips", which is based on a European standard and later published by the International Organization for Standardization (ISO), consists of the following subsections published under the same title:
In principle, the resistance of a tested pavement to stone impact is tested by projecting numerous small, sharp-edged objects onto it over a short period of time. The material used in the test consists of cooled iron grit, which is projected onto the pavement at a specific angle using compressed air. The extent of damage depends not only on the angle but also on the pressure level, the mass of the projectiles, the duration of the bombardment, and the design of the testing apparatus. Loose fragments of the pavement material are removed. The extent of damage is determined by comparison with pictorial reference standards.
Test panels with a minimum size of 100 mm x 100 mm are used for the substrate. Before coating and drying or baking, each test panel is prepared in accordance with ISO 1514. The application method specified by the paint manufacturer is used. The dry coating thickness is determined in microns using one of the procedures specified in ISO 2808.
Before performing the test, the test panels are conditioned for at least 16 hours at a temperature of 23 degrees plus/minus 2 degrees and a relative humidity of 50 percent plus/minus 5 percent (in accordance with the ISO 3270 standard).
The test is conducted at room temperature, between 18°C and 28°C. The temperature is stated in the test report. After conditioning, it is necessary to ensure that no condensation occurs before or during the test.
The tester is loaded with 500 g of sand (plus 20 g/minus 0 g). The test is performed using one of the conditions listed in the table. The method used is agreed upon between the parties involved. The sand is weighed after each test run and, if necessary, sand is added to maintain the total mass at 500 g (plus 20 g/minus 0 g). The time it takes for the sand to protrude is checked with a stopwatch each time a new test series is started, and if necessary, during an ongoing test series.
After a maximum of 100 test runs, the used grit is replaced with 500 g of fresh grit. Grit is not replaced during subsequent tests. Loose paint is removed from the test area. The method for removing loose paint is agreed upon between the parties involved and is stated in the test report.
In principle, the resistance of a tested pavement to stone impact is checked by projecting a specific impact body onto it. The impact body used in the test has a wedge-shaped cutting edge to produce a damage pattern equivalent to that obtained in a multiple impact test. The wedge-shaped impact body is forced onto the tested pavement by delivering an energy pulse from an accelerated steel ball using compressed air. Loose fragments of the pavement material are removed. Resistance to stone impact is assessed by measuring the total width of the delaminated pavement, including the wedge scar.
In principle, the resistance of a tested coating to stone impact is determined by launching a single, free-flying projectile into it in a test where the parameters that significantly influence damage (impact angle, speed, mass, and geometry of the impacting body) are defined. The temperature can be varied as needed. The test result is expressed in terms of the extent of the damaged area after removal of the coating fragments that have separated from the substrate upon impact, and in the case of multilayer paint systems, the details of the damage within each coating layer.
In principle, the resistance of a pavement to stone impact is tested by striking numerous small, sharp-edged impact bodies, fragment by fragment, largely independently of each other. The material used in the test is cold iron grit, which is projected onto the pavement at a 90-degree angle using compressed air. The extent of damage depends on the operating pressure, grit type, launch duration, and testing machine design. Loose fragments of the pavement material are removed. The degree of damage is assessed by comparison with pictorial reference standards.
In short, EN ISO 20567 is a leading international standard used to evaluate the stone chip resistance of coatings, particularly automotive paints and protective surface coatings. The test methods described play a critical role in ensuring that vehicles and other coated surfaces maintain their integrity and appearance when impacted by small, hard particles such as gravel or debris.
This standard specifies methods for assessing a coating's resistance to damage when subjected to impact from projectiles, such as stones. This standard is essential in the following sectors:
The primary goal is to simulate real-world conditions where painted surfaces may be exposed to flying stones or debris, particularly on roads, and to evaluate how durable the coating is in such scenarios.
Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, has a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the EN ISO 20567 Paints and varnishes - Determination of the resistance of coatings to stone impact.
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