BS/EN 13523-29-2017 pdf download.Coil coated metals Test methods Part 29: Resistance to environmental soiling (Dirt pick-up and striping).
This part of the EN 13523 series specifies a procedure for the comparative evaluation of resistance to soiling of an organic coating on a metallic substrate (coil coating) in an outdoor exposure environment, particularly the soiling defect known as “Tiger stripes”.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 13523-0, Coil coated metals- Test methods. Part 0: General introduction
EN 13523-19:2011, Coil coated metals – Test methods – Part 19: Panel design and method of atmospheric exposure testing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 13523-0 apply.
4 Principle
A test panel is exposed along with known reference panels, to the effects of atmospheric dirt and rain. The dirt and rain is collected and directed onto the surface of the panels in such a way as to channel rainwater thus creating the conditions to form stripes on the surface under test.
5 Apparatus and materials
5.1 Exposure rack design in accordance with EN 13523-19:2011, Clause 4 and Figure 4, modified as described below.
The area of the rack normally used for the exposure of panels to the 50 orientation is used to install a sheet made of UV stable polymeric material (e.g. polycarbonate). This sheet forms the collector of the atmospheric soil and is angled on the upper surface of the rack at between 100 and 12° with respect to the horizontal plane to control the rate of run-off of rainwater. The machining imparts grooves of 3 mm width and 3 mm depth at a separation of 3 mm extending along the surface and over the rounded edge to direct rainwater onto the panels in rivulets (see Figures 1 and 2).
The upper row of the 90° North facing exposure area of the rack is used to lix the panels, having removed the existing overhang. Two rows are used for this exposure if the panels are longer than 200 mm. The test panels are positioned so that the top edge Is in uniform contact with the bottom edge of the collector overhang.
6 Sample preparation
The test samples shall be flat and free from contamination. Sampling shall be performed in accordance with EN 13523-0. Sample dimensions shall be 100 mm x (200 mm to 400 mm).
If coil production line samples are used these should be cut so as to have the longest dimension in the direction of rolling.
7 Procedure
In addition to the test panel, expose two reference panels for each test campaign: one of known good and one of known poor performance. This allows for comparative evaluation in various atmospheric conditions.
The duration of the test is typically three months and shall be no longer than six months. The duration of the test shall be for a continuous period to avoid other weathering effects, e.g. corrosion, photo degradation, etc.
To minimize seasonal effects, the start date should be noted.
At the end of the test period there shall be sufficient separation in performance between the reference panels so as to allow a ranking of the test panels. If not, the test will be restarted with new panels.
8 Evaluation
Evaluate all panels as soon as possible after the exposure; intermediate examinations may be made (visual observations of the panels on the exposure rack).
During handling of the panels and storage before examination, care shall be taken not to disturb the dirt on the surface.
Then the test panels are compared to the reference panels and classified relative to each other and to reference panels and ranked accordingly, e.g.:
— better than the best reference panel;
— same as the best reference panel;
— in between of both reference panels;
— same as the worst reference panel;
— worse than the worst reference panel.
Changes in gloss and colour measured in accordance with EN 13523-2 and EN 13523-3 can be used to make the comparison. Record gloss and colour at points A, B and C (triplicate readings), as indicated in Figure 3.
The results should be documented by photographing the panels.
To evaluate the ease with which the panels can be cleaned, they may then be subjected to a washing procedure: Wash the left half of the panel indicated in Figure 3 with water containing 0,5 % by mass of a mild non-reactive detergent (pH 6 to pH 7) at ambient temperature. Use a cloth or sponge that is nonabrasive and smooth to gently clean the surface. Rinse with water at ambient temperature and air dry at ambient temperature.
A first evaluation is made by comparing the washed area of each panel with the unwashed area; the second evaluation is made by re-ranking the washed areas as above.BS/EN 13523-29-2017 pdf download.