Test methods, coatings

Methods for evaluating the performance of powder coatings are the same as those used for conventional coatings. Test methods for coating powders include particle size distribution, powder free flow, sintering, fluidization characteristics, and others. They have been reviewed in detail and reported in the literature (120,121). In addition, the American Society for Testing and Materials has issued a comprehensive standard that covers the most important test methods for the evaluation and characterization of powder coatings (122). 

Specifications and Standards Test Methods. Hydroxyethylcellulose is included in the Hst of materials that are in compHance with requirements of the U.S. EDA for use in adhesives and in resinous and polymeric coatings employed on the food-contact surfaces of metal, paper, or paperboard articles, and other substrates intended for use in food packaging as specified in CER 21. HEC made dispersible by cross-linking with glyoxal is cleared only as an adhesive and as a component of paper and paperboard in contact with food. It has not been cleared as a direct food additive. 

Specifications and Standards Test Methods. Ethylcellulose is cleared foi many apphcations in food and food contact under the Eedeial Eood, Dmg, and Cosmetic Act, as amended. Examples include binder in dry vitamin preparations for animal feed, coatings and inks for paper and paperboard products used in food packaging, and closures with sealing gaskets for food containers (44). Methods of analyses ate given in ASTM D914-72 (19), NationalFonmila XIV, and Food Chemicals Codex II. 

An extensive survey of accelerated test methods for anticorrosive coating performance which emphasizes the need to develop more meaningful methods of testing has been pubUshed (129). The most powerful tool available is the accumulated material in data banks correlating substrate, composition, apphcation conditions, and specifics of exposure environments with performance. 

Association of the Automotive Industry Working Group on Test Methods for Paiuts,/ Coat. Techno/. 58(734), 57 (1986). 

Sa.lt Spray Tests. One of the older accelerated corrosion tests is the salt spray test (40). Several modifications of this imperfect test have been proposed, some of which are even specified for particular appHcations. The neutral salt spray test persists, however, especially for coatings that are anodic to the substrate and for coatings that are dissolved or attacked by neutral salt fog. For cathodic coatings, such as nickel on steel, the test becomes a porosity test, because nickel is not attacked by neutral salt fog. Production specifications that call for 1000 hours salt spray resistance are not practical for quahty acceptance tests. In these cases, the neutral salt spray does not qualify as an accelerated test, and faster results from different test methods should be sought. 

A.STM B571, Std. Test Methods forMdhesion of Metallic Coatings, American Society for Testing and Materials, Philadelphia, Pa., 1991. 

ISO 2179, Ekctrodeposited Coatings of Tin—NickelMlloy, Specification and Test Methods, ISO, Geneva, Switzerland, 1986. 

Standard method for evaluation of painted or coated specimens subjected to corrosive environments Standard test method of salt spray (FOG) testing... 

Under micro-discontinuous chromium coatings, copper undercoats improve corrosion resistance. On non-conductors, especially on plastic substrates, copper is often applied before nickel-chromium plating over the initial electroless copper or nickel deposit in order to improve ductility and adhesion, e.g. as tested by the standard thermal-cycling test methods ... 

Test methods for determining electrolytic corrosion with electrical insulating materials Method for determination of resistance to intergranular corrosion of austenitic stainless steels copper sulphate-sulphuric acid method (Moneypenny Strauss test) Specification for electroplated coatings of tin/lead alloys... 

D 2803 1982 (1987) Test method for filiform corrosion resistance of organic coatings... 

D 2933 1974 (1986) Test method for corrosion resistance of coated steel specimens (cyclic method)... 

Test methods for corrosivity of solvent systems for removing water-formed deposits Recommended practice for determining corrosivity of adhesive materials Guide to the selection of test methods for coatings used in light-water nuclear power plants... 

Test method for effects of outdoor weathering on pipeline coatings Definitions of terms relating to corrosion and corrosion testing... 

This photoelastic stress analysis is a technique for the nondestructive determination of stress and strain components at any point in a stressed product by viewing a transparent plastic product. If not transparent, a plastic coating is used such as certain epoxy, polycarbonate, or acrylic plastics. This test method measures residual strains using an automated electro-optical system. 

Given the above observations it was essential in the present study that multiple test methods be used, representing evaluation of the effects of coatings on ignitability, flame spread, heat release, ease of extinction, and smoke. Samples should be commercially prepared and representative of materials commonly used in business machine applications. 

Polyester polyols, 25 464 468 Polyester resin(s), 11 302 coating resins, 7 104-106 cyclopentadiene and dicyclopentadiene applications, 8 230 flammability of, 20 115-116 properties in powder coating, 7 43t standard test methods for, 20 11 It unreinforced, 10 187t weathering of, 20 116 Polyester resin-based powder coatings, organic titanium compounds in, 25 125 Polyester resin composites, 26 762-763 Polyester resin formulations ingredients of, 20 96t unsaturated, 15 511-512 Polyesters, 10 185-189, 497 12 655-656. See also Thermoplastic polyesters Unsaturated polyesters acid resistance of, 20 7-8 antioxidant applications, 3 121 aromatic ionic, 23 722 based on 1,4-cyclohexanedimethanol, 12 674-675... 

---