ASTM D823-2018 pdf free download

ASTM D823-2018 pdf free download.Standard Practices for Producing Films of Uniform Thickness of Paint, Coatings and Related Products on Test Panels
1. Scope
1.1 Five practices are given for preparing films of uniform thickness of coatings on test panels. These practices are: Practice A—Automated Spray Machine Application Practice B—Motor-Driven Dip Coater Application Practice C—Motor-Driven Blade Film Application Practice D—Hand-Held Spray Gun Application Practice E—Hand-Held Blade Film Application 1.2 The use of wire-wound drawdown bars as described in Practice D4147 may also be an appropriate method for producing films of uniform coating thickness. 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Summary of Practices
3.1 A liquid material is applied to a test panel by means of an automated spray machine consisting ofa mounted spray gun and a panel holder. This machine can (1) move the panel holder, with test panel, at a uniform speed through the atomized spray produced by a fixed spray gun, or (2) it can move the gun, with atomized spray, at a uniform speed past the test panel(s) mounted on a fixed panel holder. A machine equipped with a programmable system can index the spray gun vertically for multiple passes and for multiple coats with selective time delay. 3.2 The thickness of coating applied is controlled by the traverse speed of the panel or gun, the fluid delivery rate of the gun, the spray gun tip size, the viscosity ofthe material, and the amount of nonvolatile matter in the material.
4. Significance and Use
4.1 This practice should be used for those coatings that are designed for spray applications of objects in the factory or in the field. It is particularly important that it be used in the evaluation of metallic coatings for appearance properties, such as gloss and color. 4.2 Coatings applied by this test method may exhibit a slight orange-peel or spray wave.
5. Apparatus
5.1 Test Panels, of any clean, planar rigid substrate with a uniform surface of a size that can be accommodated by the panel holder of the automated spray machine. 5.1.1 When steel panels are used, they should be prepared in accordance with the appropriate method in Practice D609. 5.2 Automated Spray Machine, equipped with a panel holder and a mounting for a spray gun. The machine shall be designed to move the panel holder at a uniform speed past the fixed gun mount or designed to move the gun mount at a uniform speed past the fixed panel holder. The panel holder or the gun mount traverse speed shall be adjustable from 7.5 to 30 m (25 to 100 ft)/min. Examples of automated spray machines are shown in Fig. 1. N OTE 1—Some automated spray machines provide additional features that can improve the uniformity of film preparation. Some examples are: a z-bar panel holder; indexing ofthe panel holder at right angles to the gun to provide uniform lapping; and automatic control of number of passes, time between passes, and lapping distance. 5.3 Spray Gun, any that will provide a uniform fan-type spray pattern at least 150 mm (6 in.) in width is satisfactory. The gun may be triggered manually or automatically. 5.4 Air Pressure Gage, covering the range of 0 to 690 kPa (0 to 100 psi). 5.5 Air Pressure Regulator. 5.6 Air Supply, water and oil-free, under pressure.