BS EN ISO 2409:2020 pdf – Paints and varnishes – Cross-cut test

BS EN ISO 2409:2020 pdf – Paints and varnishes – Cross-cut test.
1 Scope This document specifies a test method for assessing the resistance of paint coatings and varnishes (including wood stains) to separation from substrates when a right-angle lattice pattern is cut into the coating, penetrating through to the substrate. The property determined by this empirical test procedure depends, among other factors, on the adhesion of the coating to either the preceding coat or the substrate. This procedure is not, however, a means of measuring adhesion. NOTE 1 Where a measurement of adhesion is required, see the method described in ISO 4624. NOTE 2 Although the test is primarily intended for use in the laboratory, the test is also suitable for field testing. The method described can be used either as a pass/fail test or, where circumstances are appropriate, as a six-step classification test. When applied to a multi-coat system, assessment of the resistance to separation of individual layers of the coating from each other can be made. The test can be carried out on finished objects and/or on specially prepared test specimens. Although the method is applicable to paint on hard (e.g. metal) and soft (e.g. wood and plaster) substrates, these different substrates need a different test procedure (see Clause 8). The method is not suitable for coatings of total thickness greater than 250 µm or for textured coatings. NOTE 3 The method, when applied to coatings designed to give a rough patterned surface, will give results which will show too much variation (see also ISO 16276-2). 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1513, Paints and varnishes — Examination and preparation of test samples
4 Principle Six parallel cuts are introduced in the coating and another six cuts are introduced perpendicular to the first cuts. Any loose paint particles are removed. The cut area is examined visually and compared to a six-step classification. 5 Apparatus 5.1 General Use ordinary laboratory apparatus, together with the apparatus specified in 5.2 to 5.4. 5.2 Cutting tool 5.2.1 General requirements It is particularly important to ensure that the cutting tool is capable of creating the specified V-shape throughout the total coating thickness, and that the cutting edges are in good condition. Suitable tools are described in 5.2.2 and 5.2.3 and shown in Figures 1 and 2. A single-blade cutting tool (5.2.2) as well as the multi-blade cutting tool (5.2.3) are suitable for all coatings and substrates; it shall be ensured that all cuts mark or scratch the substrate. The depth of indentation into the substrate shall be as low as possible, however. The tools described in 5.2.2 and 5.2.3 are suitable for manual use, which is the more usual method of use, but the tools may also be mounted on a motor-driven apparatus, which gives more uniform cutting. The application of the latter procedure shall be subject to agreement between the interested parties.
5.2.2 Single-blade cutting tools 5.2.2.1 Hand-held single-blade cutting tool with a cutting edge as shown in Figure 1 a). 5.2.2.2 Single-blade cutting tool used in motor-driven apparatus as shown in Figure 3. 5.2.2.3 Cutter with a rigid blade with a V-shaped cutting edge as shown in Figure 1 b). The specific thickness of the blade is not specified, as long as the blade is rigid and the cut produced is V-shaped through the whole thickness of the coating. NOTE The cutter blade is designed to be broken in a defined manner so that a sharp blade is available at any time. 5.2.3 Multi-blade cutting tools 5.2.3.1 Hand-held multi-blade cutting tool with cutting edges as shown in Figure 2. 5.2.3.2 Multi-blade cutting tool used in motor-driven apparatus as shown in Figure 3. The multi-blade cutting tool shall have six cutting edges spaced 1 mm, 2 mm or 3 mm apart. In addition, two guide edges (see Figure 2) are necessary to make handling easier. The guide edges and the cutting edges shall lie in one plane (see Figure 2).