ISO 28199-2:2021 Paints and varnishes — Evaluation of properties of coating systems related to the spray application process — Part 2: Colour stability, process hiding power, re-dissolving, overspray absorption, wetting, surface texture and mottling

ISO 28199-2:2021 Paints and varnishes — Evaluation of properties of coating systems related to the spray application process — Part 2: Colour stability, process hiding power, re-dissolving, overspray absorption, wetting, surface texture and mottling. 1 Scope This document specifics methods for the determination of colour stability/colour evaluation, process hiding power, re-dissolving, overspray absorption, wetting, surface texture and mottling of coating materials applied to a test panel under defined conditions, using spray application process. 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 28199-1:2021, Paints and varnishes — Evaluation of properties of coating systems related to the spray application process — Part 1: Vocabulary and preparation of test panels 3 Terms and defInitions For the purposes of this document, the terms and definitions given in ISO 28199-1 apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https://wwwJso.org/obp — IEC Electropedia: available at http://www.electropedia.org/ 4 Colour stability/colour evaluation 4.1 General Colour stability is determined by evaluation of the values measured for a wedge-shaped base coat and constant-thickness clear coat, obtained in accordance with ISO 28199-1:2021, 9.4. 4.2 Evaluation Plot the colour space values determined for the wedge-shaped base coat and constant-thickness clear coat in accordance with ISO 28199-1:2021, 9.4, against the film thickness of the base coat, and evaluate the curve. Determine the lowest (tmjn) and the highest (tmaj film thicknesses at which the curve is approximately parallel to the X-axis. With regard to parallelism, a tolerance range or a minimum gradient is agreed. Figures 1 and 2 show examples of lightness (L*) plotted against film thickness. The Y-axis can also show the colour values a*, b*, C and h. 5 Process hiding power 5.1 General The process hiding power is determined by evaluation of the values measured for the process substrate, wedge-shaped base coat and constant-thickness clear coat, obtained in accordance with ISO 28199-1:2021, 9.4. The lowest film thickness exhibiting colour stability (t min ) (see 4.2) is determined. 5.2 Evaluation Using the same method for evaluating the colour stability as specified in 4.2, evaluate the values measured for the process substrate, wedge-shaped base coat and...