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, examine the test area using the microscope (5.5).
Turn the test arcs of the panel through 90 and repeat the procedure.
6.3.4 Assessment of resuks
Rite the test areas according to th. descriptive numerical rating code in Table I (see also Figure 3).BS EN 927-13 pdf download.