ISO 3248 pdf download.Paints and varnishes — Determination of the effect of heat
1 Scope
This International Standard is one of a series of standards dealing with the sampling and testing of paints, varnishes and related products. It specifies a general procedure for determining the resistance of single coatings or multi-coat systems of paints, varnishes or related products to changes in gloss and/or colour, blistering, cracking and/or detachment from the substrate under conditions of moderately elevated temperature. This procedure is applicable to products intended for use on domestic radiators or other articles likely to be subjected to similar temperatures.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 1 51 2:1 991 , Paints and varnishes — Sampling of products in liquid or paste form . ISO 1 51 3:1 992, Paints and varnishes — Examination and preparation of samples for testing. ISO 1 51 4:1 993, Paints and varnishes — Standard panels for testing. ISO 1 51 8:1 992, Paints and varnishes — Scratch test. ISO 1 51 9:1 973, Paints and varnishes — Bend test (cylindrical mandrel). ISO 1 520:— 1 ) , Paints and varnishes — Cupping test. ISO 2808:1 997, Paints and varnishes — Determination of film thickness. ISO 6272:1 993, Paints and varnishes — Falling-weight test.
3 Required supplementary information
For any particular application, the test method specified in this International Standard needs to be completed by supplementary information. The items of supplementary information are given in annex A.
4 Sampling
Take a representative sample of the product to be tested (or of each product in the case of a multi-coat system), as specified in ISO 1 51 2. Examine and prepare each sample for testing, as specified in ISO 1 51 3.
5 Test panels
5.1 Substrate Unless otherwise specified the test panels shall be of steel, tinplate, aluminium or glass as appropriate and shall comply with the requirements of ISO 1 51 4. Unless otherwise specified, the panels shall be 1 50 mm ¥ 1 00 mm. 5.2 Preparation and coating Unless otherwise specified, prepare each test panel in accordance with ISO 1 51 4 and then coat it by the specified method with the product or system under test. 5.3 Drying and conditioning Dry (or stove) and age (if applicable) each coated test panel for the specified time and under the specified conditions and, unless otherwise specified, condition at (23 ± 2) °C and a relative humidity of (50 ± 5) % for a minimum of 1 6 h. The test procedure shall then be carried out as soon as possible. 5.4 Thickness of coating Determine the thickness, in micrometres, of the dried coating by one of the procedures specified in ISO 2808.
6 Procedure
6.1 Temperature and duration of test Carry out the test procedure at (1 25 ± 2) °C for a period of 24 h, unless otherwise agreed. 6.2 Determination Place the panels in an oven with air circulation at the specified temperature, not less than 1 00 mm from the sides of the oven and not closer than 20 mm apart, and maintain them at that temperature for the specified time. The preferred method of ensuring even heating of the coated panels is to suspend them by means of fine wires. Alternatively, the panels may be supported in a rack made from suitable heat-resistant material or placed, paint side uppermost, on a piece of heat-resistant board resting on supports. At the end of the specified time, remove the panels from the oven and allow them to cool to a temperature of (23 ± 2) °C. Examine the panels for change of colour or signs of other deterioration of the coating, by comparison with identically prepared, but unheated, panels. When specified, subject both heated and unheated panels, not less than 1 6 h after completing the heating period, to one of the test procedures specified in ISO 1 51 8, ISO 1 51 9, ISO 1 520 or ISO 6272, or to other agreed test procedures, and examine for compliance with the specified requirement.