EN ISO 2420:2017 pdf download.Leather – Physical and mechanical tests – Determination of apparent density and mass per unit area [ISO 2420:2017).
6 Sampling and sample preparation
Sample in accordance with ISO 2418. From the sample, cut three test pieces by applying the press knife (&1) to the grain surface and condition them in accordance with ISO 2419,
If there isa requirement for more than two hides or skins to be tested in one batch, then only one test piece needs to be taken from each hide or skin, provided that the overall total is not less than three test pieces.
7 Procedure
7.1 Test conditions
Carry out all operations in a standard atmosphere as specified in ISO 2419.
7.2 Measurement of thickness
Measure the thickness of each test piece in accordance with ISO 2589. Measure the thickness, in millimetres. at three points forming the corners of an equilateral triangle, with each situated approximately 20 mm from the centre of the test piece. Measure the thickness at the centre of the test piece. Take the arithmetic mean of the four results as the thickness of the test piece, t.
NOTE The centre of the test piece and the other points for measurement are estimated by eye.
7.3 Measurement of dimensions
For circular test pieces, measure the diameter using Vernier callipers (SA) to the nearest 0,05 mm in two directions at right angles to each other on the grain surface and two directions at right angles on the flesh surface. Take the arithmetic mean of the four results as the mean diameter of the test piece, d. Reject any test piece where the diameters on either the grain surface or the flesh surface differ by more than 0,5 mm.
For square test pieces, measure the distances AC and BD, where A, B, C and D are the midpoints of each side to within 0,5 mm, using Vernier callipers (5A) to the nearest 0,05 mm as shown in Figure 1. Measure the distances on both the grain surface and on the flesh surface. Take the arithmetic mean of the results for the two results of AC, a, and BD, b, respectively. Reject any test piece where the distance measured on the grain surface differs more than 0,5 mm from the distance measured on the flesh surface.EN ISO 2420 pdf download.