BS EN 927-13-2019 Paints and varnishes一Coating materials and coating systems for exterior wood Part 13: Assessment of resistance to impact of a coating on a wooden substrate

BS EN 927-13-2019 Paints and varnishes一Coating materials and coating systems for exterior wood Part 13: Assessment of resistance to impact of a coating on a wooden substrate. The test panel shall be placed in a stable position on the horizontal base (5.1) in such way that all impact points are inside the area covered by the base. The tests should be cirTied out a an ambient temperature of(23 t 2)C. and at a relative humidity o (50t5)%, 6.32 Impact test On each panel make six impacts train each of the Iollowrng dropping heights: 10mm: 25 mm; 50mm and 100 mm. The dropping height. wluch shall be measured within ± 0.5mm, is the distance from the top of the ball to the bottom surface of the wesghL Either make a random selection of impact sites, making provision to identify the dropping height for each site adequately, or preferably use the grid pattern described In 6.31 makIng three Impacts on each numbered line with dropping heights as follows: — online I Iromadroppingheightoflomm; — on hne 2 from a dropptng heIght of 25 mm; — on line 3 from a dropping height of 50mm; — on line 4 from a dropping height ol 100 mm; — on line S from a droppmg height of 10mm; — on line 6 Irons a dropping height o125 mm. — on line 7 from a dropping height of 50mm; — onhne8homadroppangheightofloomm. For each test, position the guide tube (5.2) on the test area with the ball (5.4) In direct contact with the surface. Drop the cylindrical weight (5.3) once from the specified bright onto the balL Alter each test, the ball should be examined for possible deformation and If necessary replaced by an undamaged bilL After completion of the test, the application of penetrating stain or other swtable mailcer (like whiteboard marker of suitable colour) to the test area can assist with the Identiflcatlon of surface cradcs. After few seconds ilter marking carrfully wipe the unpact mark with he soft paper towel to remove residue of the marker. 6.3.3 ExamInation of test panel Carefully examine the test area under magnification and good direct light using the following procrdure Keeping the teSt area directly under the light, rock the panel or the light. so that the angle between the direction of the light and the plane of the panel varies between 0 and 3. During the rocking movement,...