1、Designation: D823 17Standard Practices forProducing Films of Uniform Thickness of Paint, Varnish,and Related Products on Test Panels1This standard is issued under the fixed designation D823; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 Five practic
3、es are given for preparing films of uniformthickness of coatings on test panels. These practices are:Practice AAutomatic Spray Machine ApplicationPractice BMotor-Driven Dip Coater ApplicationPractice CMotor-Driven Blade Film ApplicationPractice DHand-Held Spray Gun ApplicationPractice EHand-Held Bla
4、de Film Application1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standa
5、rd to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on
6、Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint, Varnish, Conv
7、ersion Coatings, andRelated Coating ProductsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base (Withdrawn 2006)3D1212 Test Methods for Me
8、asurement of Wet Film Thick-ness of Organic CoatingsD1400 Test Method for Nondestructive Measurement of DryFilm Thickness of Nonconductive Coatings Applied to aNonferrous Metal Base (Withdrawn 2006)3D3924 Specification for Standard Environment for Condi-tioning and Testing Paint, Varnish, Lacquer, a
9、nd RelatedMaterials (Withdrawn 2016)3PRACTICE AAUTOMATIC SPRAY MACHINEAPPLICATION3. Summary of Practices3.1 A liquid material is applied to a test panel by means ofan automatic spray machine consisting of a mounted spray gunand a panel holder. This machine can (1) move the panelholder, with test pan
10、el, at a uniform speed through theatomized spray produced by a fixed spray gun, or (2)itcanmove the gun, with atomized spray, at a uniform speed past thetest panel mounted on a fixed panel holder. A machineequipped with a programmable system can index the spray gunvertically for multiple passes and
11、for multiple coats withselective time delay.3.2 The thickness of coating applied is controlled by thetraverse speed of the panel or gun, the fluid delivery rate of thegun, the viscosity of the material, and the amount of nonvola-tile matter in the material.4. Significance and Use4.1 These practices
12、should be used for those coatings thatare designed for spray applications of objects in the factory orin the field. It is particularly important that it be used in theevaluation of metallic coatings for appearance properties, suchas gloss and color.1These practices are under the jurisdiction of ASTM
13、 Committee D01 on Paintand Related Coatings, Materials, and Applications and are the direct responsibilityof Subcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved Dec. 1, 2017. Published December 2017. Originallyapproved in 1945. Last previous edition approved in
14、 2012 as D823 95 (2012)1.DOI: 10.1520/D0823-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last appr
15、oved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization
16、 established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14.2 Coatings applied by this test method may exhibit a slightorange-peel or spray wave.5. Apparatus
17、5.1 Test Panels, of any smooth, planar material of a size thatcan be accommodated by the panel holder of the automaticspray machine.5.1.1 When steel panels are used, they should be prepared inaccordance with the appropriate method in Practice D609.5.2 Automatic Spray Machine, equipped with a panel h
18、olderand a mounting for a spray gun. The machine shall be designedto move the panel holder at a uniform speed past the fixed gunmount, or designed to move the gun mount at a uniform speedpast the fixed panel holder. The panel holder or the gun mounttraverse speed shall be adjustable from 7.5 to 30 m
19、 (25 to 100ft)/min. Typical machines are shown in Fig. 1.NOTE 1Some automatic spray machines provide additional featuresthat can improve the uniformity of film preparation. Some examples are:a z-bar panel holder; indexing of the panel holder at right angles to the gunto provide uniform lapping; and
20、automatic control of number of passes,time between passes, and lapping distance.5.3 Spray Gun, any that will provide a uniform fan-typespray pattern at least 150 mm (6 in.) in width is satisfactory.The gun may be triggered manually or automatically.5.4 Pressure Gage, covering the range of 0 to 690 k
21、Pa (0 to100 psi).5.5 Air Pressure Regulator.5.6 Air Supply, oil-free, under pressure.6. Preparation of Apparatus6.1 Mount the spray gun on the automatic spray machine.Connect the air line hose from the regulator to the air pressuregage which in turn is connected to the air inlet of the spray gun.6.2
22、 Set the gun so that its tip is at the desired distance fromthe test panel surface, usually in the range from 200 to 300 mm(8 to 12 in.).6.3 With the gun trigger fully open, adjust the air regulatorto provide the desired reading on the air pressure gage.NOTE 2A suitable air pressure is usually from
23、275 to 520 kPa (40 to75 psi).6.4 Set the automatic spray machine controls to provide thedesired traverse speed of the panel holder or the gun mount,whichever is pertinent to the type of machine being used.NOTE 3Suitable traverse speeds for automative coatings usually rangefrom 17.5 to 22.5 m/min (70
24、0 to 900 in./min ).7. Procedure7.1 Strain the material to be sprayed into the container to beused with the spray gun. Reduce the material to a viscositysuitable for spraying.7.2 Connect the container to the gun and test the spray gunoperation while stationary, for correct spray pattern and uni-formi
25、ty by allowing a momentary spray to be deposited on apiece of paper placed in the panel position. Adjust the airpressure material flow, and spray fan width controls until thedesired pattern and uniformity are obtained. Further refine-ments may be made in the spray pattern by modifying the airpressur
26、e, the type of thinning agent, and the consistency of thematerial.NOTE 4The width of the spray pattern should be considerably widerthan the width of the test panel to assure spray uniformity on the testpanel.7.3 Place a test panel on the panel holder and start themachine. Operate the spray gun so th
27、at it will begin spraying afew seconds before the test panel enters the spray pattern andcontinue spraying a few seconds after the test panel leaves thespray pattern.7.4 Remove the coated panel and bake, force-dry, or air-dryit, in accordance with its type, in a vertical position in adust-free atmos
28、phere, as described in Specification D3924.7.5 Determine the thickness of the coating in accordancewith Test Methods D1005, D1186, D1212,orD1400, which-ever is appropriate.8. Report8.1 Report the following information:8.1.1 Type of coating material,8.1.2 Viscosity and percent of nonvolatile coating
29、material,8.1.3 Distance of test panel from gun tip,8.1.4 Air pressure,8.1.5 Number of spray passes,8.1.6 Traverse speed,8.1.7 Temperature and relative humidity at time ofapplication, and8.1.8 Film thickness values obtained for applied coating.PRACTICE BMOTOR-DRIVEN DIP COATERAPPLICATION9. Summary of
30、 Practice9.1 A motor-driven device is employed to withdraw the testpanel from a container of the coating material at a desireduniform rate.9.2 The thickness of coating applied is controlled by thespeed of panel withdrawal, the viscosity of the material, andthe percent of solids in the material.10. S
31、ignificance and Use10.1 This test method is limited to those materials that flowout to smooth films when test panels are dipped into thematerial and withdrawn.11. Apparatus11.1 Dip Coater, consisting of a mechanism that will with-draw a panel from a container of the coating material at apredetermine
32、d rate. Suitable apparatus, is shown in Fig. 2(a)and 2(b):11.1.1 The apparatus shown in Fig. 2(a) uses a cord woundaround a step-cone pulley on the shaft of a motor to providepanel withdrawal rate of 50, 75, and 100-mm (2, 3, and4-in.)/min. Prior to withdrawal, the panel, attached to the cord,is low
33、ered by hand into the container holding the material.D823 172(a) Fixed Gun, Traveling Panel Machine (b) Fixed Panel, Traveling Gun Machine(c) Fixed Panel Programmable Indexing Traveling Gun MachineFIG. 1 Automatic Spray Machines, Practice AD823 17311.1.2 The apparatus shown in Fig. 2(b) uses a cord
34、drivenby a variable-speed device that can provide panel immersionand withdrawal rates that are continuously variable from 65 to510 mm (2.5 to 20 in.)/min.NOTE 5Rectangular containers (F-style can with lid cut off) are usefulbecause the smaller exposed surfaces of the liquid coating reduces volatilel
35、oss.11.2 Test Panels, of any clean, smooth, rigid substrate of asize that can be accommodated by the dip coater and thecontainer.11.2.1 When steel panels are used they shall be prepared inaccordance with the appropriate method in Practice D609.NOTE 6The test panels should not exceed 300 mm (12 in.)
36、in length,but the width may be varied up to 300 mm (12 in.) if a suitablecounterweight is used and a dip tank of adequate size is provided. Use ofa multiple hook will permit dipping several panels at one time.12. Procedure12.1 Adjust the coating material to the proper percentage ofsolids and viscosi
37、ty. Measure the temperature of the material inthe container at the time of application.NOTE 7The operating conditions (viscosity, percent of nonvolatilematter, and rate of withdrawal) are specific for a given coating materialand film thickness and need to be determined by trial. Subsequentreproducti
38、on of the same operating conditions should give the same filmthickness. Data are available4on a variety of materials and film thicknessto indicate the range required. The viscosity range for normal filmthickness of 13 to 50 mm (0.5 to 2.0 mil ) has been shown to be 1 to 2.5P.12.2 Place the prepared
39、test panel on the hook attached tothe cord and lower it into the container holding the coatingmaterial. Wind the cord once completely around the pulley ofthe correct size to give the desired rate of withdrawal.12.2.1 For the stepped-cone pulley apparatus, wind the cordonce completely around the pull
40、ey of the correct size to givethe desired weight of withdrawal.12.2.2 For the continuously variable speed apparatus set thedesired panel immersion and withdrawal rates on the controlpanel.12.3 Start the motor and withdraw the panel at the desiredrate, with a smooth movement entirely free of vibratio
41、n. Bake,force-dry, or air-dry the coated panel, in accordance with itstype, in a vertical position in a dust-free atmosphere inaccordance with Specification D3924.4Information covering viscosity, percent of solids, rates of withdrawal and filmthickness for a variety of finishing materials is given i
42、n the paper by Payne, H. F.,“The Dip Coater, An Instrument For Making Uniform Films by the Dip Method,”Industrial and Engineering Chemistry, Analytical Edition, Vol 15, 1943, p. 48.(a) Dip-Coater With Motor-Driven Step-Cone Pulley (b) Dip-Coater With Continuously Variable Speed DriveFIG. 2 Dip-Coate
43、r, Practice BD823 17412.4 Determine the thickness of the coating in accordancewith Test Methods D1005, D1186,orD1400, whichever isappropriate.12.5 If the coating thickness is too low, coat another panelusing a slower rate of panel withdrawal. If the coatingthickness is too high, coat another panel u
44、sing a faster rate ofpanel withdraw.12.6 Continue in this manner until a test panel having thedesired film thickness is produced. Measure thickness on atleast three different areas of the test panel to determine coatinguniformity.NOTE 8With the dip coater, non-uniform thickness on a panel isfrequent
45、ly obtained. Hence, if the film thickness is greater at the bottomthan the top, the viscosity should be increased or the panel withdrawalspeed should be reduced, or both.13. Report13.1 Report the following information:13.1.1 Type of coating material,13.1.2 Viscosity, temperature, and percent nonvola
46、tile ofcoating material,13.1.3 Rate of withdrawal,13.1.4 Air temperature and relative humidity at time ofapplication, and13.1.5 Mean and range of dry film thickness values ob-tained.PRACTICE CMOTOR-DRIVEN BLADE FILMAPPLICATION14. Summary of Practice14.1 A uniform film is produced by an applicator bl
47、ade thatis pushed across the test panel at a uniform speed by amotor-driven device.14.2 The thickness of coating applied is controlled by theclearance of the applicator blade and the viscosity and percent-age of solids of the material.15. Significance and Use15.1 This test method is applicable to su
48、bstrates consistingof smooth rigid materials, such as metal or glass, and ofnon-rigid materials, such as paper charts. It is more reliable forproducing uniform films than is the use of hand-held draw-down applicators.16. Apparatus16.1 Motor-Driven Blade Film Applicator,5consisting of abase plate, a
49、bar for holding an applicator blade, and a drivingmechanism. The base plate shall hold paper charts flat bymeans of a vacuum. The blade holder shall be designed toaccommodate common types of applicator blades, and de-signed to accept weights for loading the applicator blade, ifnecessary, to prevent lifting of the blade when applying viscousmaterials. A mechanism shall be provided to stop the blademovement automatically at the end of the draw-down. Asuitable apparatus is shown in Fig. 3.16.2 Vacuum Source, a vacuum pump or a water aspirator.16.3 Applicator Blade,
