BS ISO 21546:2019 pdf free.Paints and varnishes – – Determination of the resistance to rubbing using a linear abrasion tester (crockmeter).
A loaded abrasion tool, lined with agreed abrasive material and influenced by an agreed abrasive medium, is moved over the coating using a linear abrasion tester (crockmeter). There are three procedure variations, depending on the agreement and application (see Table 1).5 Apparatus and ancillary materials
5.1 Linear abrasion tester (crockmeter) Linear abrasion tester in accordance with Figure 1, which is specified by the following properties.5.1.1 The mechanism can be manual (as illustrated in Figure 1) or (electro) motor driven.5.1.2 For the motoric version, an operation counter for pre-setting the number of double-strokes shall be integrated and the mechanism shall have a stroke frequency of (1,0 ± 0,1) Hz and shall have a constant velocity within the 70 mm measurement area.5.1.3 The test load with which the abrasion tool (52) is pressed onto the test specimen shall be (9,0 ± 02) N (for abrasion tool B and C) and (2 2,0 ± 05) N (for abrasion tool A).NOTE Test devices intended for a test load of 9,0 N can be converted to a test load of 22,0 N by means of an additional load of 13,0 N (corresponding to an additional weight with a mass of 133 kg).5.1.4 The stroke length shall be selected in such a way that the length of the assessable friction mark is (100 ± 30) mm.NOTE 1 The assessable friction mark equals the total friction mark, less the expansion of the contact surface of the abrasion tool in the direction of the stroke on both ends (see 7.3.1). Consequently, the stroke length is at least 70 mm + 2 x expansion, in millimetres, of the contact surface of the abrasion tool in the direction of the stroke. For the dimensions of the abrasion tools, see 52.NOTE 2 Some devices exist with a length of the assessable surface less than 70 mm due to technical reasons.BS ISO 21546 pdf download.