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ASTM International has revised Standards D2197 and D4541, regarding test methods for adhesion of organic coatings and for pull-off strength of coatings.
D2197 - Standard Test Method for Adhesion of Organic Coatings by Scrape Adhesion, developed by Subcommittee D01.23 (Physical Properties of Applied Paint Films), has been found useful in differentiating the degree of adhesion of coatings to substrates. It is most useful in providing relative ratings for a series of coated panels exhibiting significant differences in adhesion.
Studies performed in a laboratory using the loop stylus specified in the previous edition showed meaningful adhesion data were impossible when loads of 10 to 20 kg were required to break the surface of a solvent-based coating. The chrome-plated loop stylus chattered and skipped across the coating surface when loads of this magnitude were required. Similar meaningless data were obtained when powder coatings were tested that required more than 10 kg to break the surface. Therefore, testing under these conditions is not applicable.
This test method covers the determination of the adhesion of organic coatings such as paint, varnish and lacquer when applied to smooth, flat (planar) panel surfaces.
D4541 - Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers, developed by Subcommittee D01.46 (Industrial Protective Coatings), serves as a means for uniformly preparing and testing coated surfaces, and evaluating and reporting the results. This test method is applicable to any portable apparatus meeting the basic requirements for determining the pull-off strength of a coating.
This test method covers a procedure for evaluating the pull-off strength (commonly referred to as adhesion) of a coating system from metal substrates. Pull-off strength of coatings from concrete is described in Test Method D7234. The test determines either the greatest perpendicular force (in tension) that a surface area can bear before a plug of material is detached, or whether the surface remains intact at a prescribed force (pass/fail).
Variations in results obtained using different devices or different substrates with the same coating are possible. Therefore, it is recommended that the type of apparatus and the substrate be mutually agreed upon between the interested parties.
The purchaser or specifier shall designate a specific test method (that is, B, C, D, E, or F) when calling out this standard.
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