ISO 2409:1992 pdf download – Paints and varnishes – Cross-cut test
1.1 This International Standard is one of a series of standards dealing with the sampling and testing of paints, varnishes and related producls. |t specifies a test method for assessing the resistance of paint coatings to separation from substrates when a right-angle lattice pattern is cut into the coating, penelrating through to the substrate. The properly measured 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 to be regarded, however, as a means of measuring adhesion. Where a measurement of adhesion is required, at- tention is drawn to the method described in ISO 4624:1978, Paints and varnishes – Pul/-off test for adhesion. NOTE 1 Although the test is primarily intended for use in the labor atory, the test is also suitable for field lesting.
1.2 The method described may be applied either as a pass/fail test or, where circumstances are ap- propriate, as a six-step classification test (see 8.3). When applied to a multi-coat system, assessment of the resistance to separation of individual layers of the coating from each other may be made.
1.3 The test may be carried out on finished objects and/or on specially prepared test specimens. Although the method is applicable to paint on hard (steel) and soft (wood and plaster) substrates, these difTerent substrates need a different test procedure (see clause 7). The method is not suitable for 。coatings of total thlckness greater than. 250 μm or for textured coatings.
7.2.3 Hold the cutting tool {4.1) with the blade normal to the test panel surface. With uniform pressure on the cutting tool and using the appropri- ate spacing guide (4.2), make the agreed number of cuts in the coating at a uniform cutting rate. All the cuts shall penetrate to the substrate surface. If it is not possible, due to the hardness of the coat- ing, to penetrate to the substrate, the test shall be declared invalid and so reported.
7.2.4 Repeat this operation, making further parallel cuts of equal number, crossing the original cuts at 90° to them so that a lattice pallern is formed.
7.2.5 Brush the panel lightly with the soft brush (4.3) several times backwards and several times forwards along each of the diagonals of the lattice pattern.
7.2.6 For hard substrates only, apply additionally adhesive tape (4.4). If beginning a new series of tests, remave two complete laps from a reel of the adhesive tape and discard. Remove an additional length at a steady rate and cut a piece approxi- mately 75 mm long. Place the centre of the tape over the lattice in a di- rection parallel to one set of cuts as shown in figure 3 and smooth the tape into place over the area of the lattice and for a distance of at least 20 mm beyond with a finger. To ensure good contact with the coating, rub the lape firmly with a fingertip. The colour of the coating seen through the tape is a useful indication of over- all contact. Within 5 min of applying the tape, remove the tape by grasping the free end and pulling t off steadily in 0.5s to 1,0s at an angle which is as close as poss- ible to 60° (see figure 3).