The standard “ASTM D4828-94 Standard test methods for practical washability of organic coatings” developed by the American Society for Testing and Materials (ASTM) describes test methods for determining the relatively easy removal of common soils and stains from interior coatings by manual or mechanical washing with a sponge and liquid or powder cleaner.
When performing these tests, the test material is applied to a plastic panel and allowed to dry for 7 days or as mutually agreed upon. Contaminants or stains or both are applied to the film. The film is washed up to 100 cycles using a sponge and liquid or powder cleaner. After rinsing and drying, the panel is evaluated for degree of dirt or stain removal, abrasion and gloss or color change between washed and unwashed areas.
Interior architectural paints are subject to contamination by dirt or other stains during use. This test method provides a means of evaluating the ease of dirt or stain removal from a paint film using materials commonly used in homes. This test method includes a means of evaluating the film for washability characteristics and changes in appearance. Thus, a formulator can evaluate the effects of composition on the washability characteristics of a paint. Users can also compare the ease of dirt removal from different paints tested, preferably simultaneously.
Major equipment used in testing includes:
When performing the tests, the top of the glass plate and both sides of the black plastic panel are cleaned to ensure they are free of smudges. The black panel is placed on the glass plate and one end is taped to the plate. The panel is smoothed across the plate to ensure a tight fit.
The material is thoroughly mixed and, if necessary, filtered to remove all crusts and particles. The coating is drawn onto the panel. To prevent pinholes or breaks in the film, the coating is applied edge-to-edge in 3 to 4 seconds. A sufficient number of panels are prepared with each paint for all intended tests. All panels are dried horizontally for 7 days at a temperature of 23 degrees plus/minus 2 degrees and 50 percent plus/minus 5 percent relative humidity, as described in “ASTM D3924-16 Standard specification for the conditioning and testing of paints, varnishes, lacquers and related materials” or under conditions applicable specifically to the material being tested. If desired, an additional panel can be prepared from each paint to check for unwashed paint.
After the drying period is complete, the coated panel is taped to the glass sheet as specified in this standard to ensure uniform application of contaminants and stains. The selected contaminants or stains, or both, are applied to the coating film in straight double lines parallel to the length of the panel for the manual cleaning method or perpendicular to the length of the panel for the mechanical cleaning method.
Solid contaminants or dyes are applied using the apparatus shown in the figure given in the standard. A pencil, crayon, pen or similar object is inserted into the appropriately sized hole and fixed so that it extends 40 mm beyond the panel.
The medium is secured with a piece of masking tape. The applicator is placed at one end of the coated plastic panel and the 100g weight is placed on the top face of the wooden panel at the end closest to the marking device and secured with a piece of tape.
The weightless tip of the applicator is allowed to rest on the surface of the film, then grasped by the outer edges and pulled along the entire length of the film.
Among the numerous tests, measurements, analyses and evaluation studies carried out for businesses in various sectors, our organization also provides testing services defined in the "ASTM D4828-94 Standard test methods for practical washability of organic coatings" standard with its trained and expert staff and advanced technological equipment.
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