1、Designation: D823 18Standard Practices forProducing Films of Uniform Thickness of Paint, Coatingsand 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 AAutomated 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 use of wire-wound drawdown bars as described inPractice D4147 may also be an appropriate method forproducing films of uniform coating thickness.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4
5、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 standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5
6、 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Tr
7、ade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint, Varnish, Conversion Coatings, andRelated Coating ProductsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD1212 Test
8、 Methods for Measurement of Wet Film Thick-ness of Organic CoatingsD3924 Specification for Standard Environment for Condi-tioning and Testing Paint, Varnish, Lacquer, and RelatedMaterials (Withdrawn 2016)3D4147 Practice for Applying Coil Coatings Using Wire-Wound Drawdown BarsD4285 Test Method for I
9、ndicating Oil or Water in Com-pressed AirD4414 Practice for Measurement of Wet Film Thickness byNotch GagesD7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic, Nonconductive Coat-ings Applied to Non-Ferrous MetalsPRACTIC
10、E AAUTOMATED SPRAY MACHINEAPPLICATION3. Summary of Practices3.1 A liquid material is applied to a test panel by means ofan automated spray machine consisting of a mounted spray gunand a panel holder. This machine can (1) move the panelholder, with test panel, at a uniform speed through theatomized s
11、pray produced by a fixed spray gun, or (2)itcanmove the gun, with atomized spray, at a uniform speed past thetest panel(s) mounted on a fixed panel holder. A machineequipped with a programmable system can index the spray gunvertically for multiple passes and for multiple coats withselective time del
12、ay.3.2 The thickness of coating applied is controlled by thetraverse speed of the panel or gun, the fluid delivery rate of thegun, the spray gun tip size, the viscosity of the material, and theamount of nonvolatile matter in the material.1These practices are under the jurisdiction of ASTM Committee
13、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 March 1, 2018. Published March 2018. Originallyapproved in 1945. Last previous edition approved in 2017 as D823
14、 17. DOI:10.1520/D0823-18.2For 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 approved version of this
15、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 established in the D
16、ecision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14. Significance and Use4.1 This practice should be used for those coatings that aredesigned for spray applications of ob
17、jects in the factory or inthe field. It is particularly important that it be used in theevaluation of metallic coatings for appearance properties, suchas gloss and color.4.2 Coatings applied by this test method may exhibit a slightorange-peel or spray wave.5. Apparatus5.1 Test Panels, of any clean,
18、planar rigid substrate with auniform surface of a size that can be accommodated by thepanel holder of the automated spray machine.5.1.1 When steel panels are used, they should be prepared inaccordance with the appropriate method in Practice D609.5.2 Automated Spray Machine, equipped with a panelhold
19、er and a mounting for a spray gun. The machine shall bedesigned to move the panel holder at a uniform speed past thefixed gun mount or designed to move the gun mount at auniform speed past the fixed panel holder. The panel holder orthe gun mount traverse speed shall be adjustable from 7.5 to 30m (25
20、 to 100 ft)/min. Examples of automated spray machinesare shown in Fig. 1.NOTE 1Some automated 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 unifo
21、rm 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-typespray 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
22、 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.6. Preparation of Apparatus6.1 Mount the spray gun on the automated spray machine.Connect the air line hose from the regulator to the air pressuregage which in turn is connected to the
23、air inlet of the spray gun.6.2 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
24、 air pressure is usually from 275 to 520 kPa (40 to75 psi).6.4 Set the automated 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 automotive coatings usually ra
25、ngefrom 17.5 to 22.5 m/min (700 to 900 in./min).7. Procedure7.1 If compressed air is used to atomize the coating, verifythat the air is clean and dry according to Test Method D4285.7.2 If recommended by the coating manufacturer, strain thematerial to be sprayed into the container to be used with the
26、spray gun. Reduce the material to a viscosity suitable forspraying using the coating manufacturers recommended thin-ner.7.3 Connect the container to the gun and test the spray gunoperation while stationary, for correct spray pattern and uni-formity by allowing a momentary spray to be deposited on ap
27、iece 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 airpressure, and the type and amount of thinner.NOTE 4The width
28、 of the spray pattern should be considerably widerthan the width of the test panel to assure spray uniformity on the testpanel.7.4 Place a test panel on the panel holder and start themachine. Operate the spray gun so that it will begin spraying afew inches before the test panel enters the spray patt
29、ern andcontinue spraying a few inches after the test panel leaves thespray pattern.7.5 Measure the wet film thickness in accordance with TestMethods D1212 or Practice D4414. Additional passes may bemade until the desired wet film thickness has been achieved.7.6 Remove the coated panel and bake, forc
30、e-dry, or air-dryit, in accordance with its type, in a vertical position in adust-free atmosphere (if required), as described in Specifica-tion D3924.7.7 Measure the dry film thickness of the coating in accor-dance with Test Methods D1005 or Practice D7091, whicheveris appropriate.8. Report8.1 Repor
31、t the following information:8.1.1 Type of coating material,8.1.2 Type and amount of thinner added as a percentage byweight or volume of the total mixed coating, if applicable,8.1.3 Temperature of coating material,8.1.4 Wet film thickness,8.1.5 Distance of test panel from gun tip,8.1.6 Type of spray
32、gun and spray tip size,8.1.7 Air pressure,8.1.8 Number of spray passes,8.1.9 Traverse speed,8.1.10 Air temperature, relative humidity and temperatureof test panel at time of application, and8.1.11 Mean and range of dry film thickness values ob-tained.D823 182(a) Fixed Gun, Traveling Panel Machine (b
33、) Fixed Panel, Traveling Gun Machine(c) Fixed Panel Programmable Indexing Traveling Gun MachineFIG. 1 Automatic Spray Machines, Practice AD823 183PRACTICE BMOTOR-DRIVEN DIP COATERAPPLICATION9. Summary of Practice9.1 A motor-driven device is employed to withdraw the testpanel from a container of the
34、coating material at a desireduniform rate.9.2 The wet film thickness of the applied coating is influ-enced by many variables including, but not limited to the speedof withdrawal, rheological characteristics of the coating at thetest temperature and the temperature of the test panel.10. Significance
35、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 apredetermined rate. Suit
36、able 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 lowered by hand
37、 into the container holding the material.11.1.2 The apparatus shown in Fig. 2(b) uses a cord 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 cu
38、t off) are usefulbecause the smaller exposed surfaces of the liquid coating reduces volatileloss.11.2 Test Panels, of any clean, rigid substrate with auniform surface of a size that can be accommodated by the dipcoater and the container.11.2.1 When steel panels are used they shall be prepared inacco
39、rdance with the appropriate method in Practice D609.NOTE 6The test panels should not exceed 300 mm (12 in.) 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 pa
40、nels at one time.(a) Dip-Coater With Motor-Driven Step-Cone Pulley (b) Dip-Coater With Continuously Variable Speed DriveFIG. 2 Dip-Coater, Practice BD823 18412. Procedure12.1 Adjust the coating material to the desired viscosityusing thinner as necessary. Measure the temperature of thematerial in the
41、 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. Subsequentreproduction of the same operating conditions should yield
42、a similar filmthickness.12.2 Place the prepared 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 apparat
43、us, wind the cordonce completely around the pulley 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,
44、with a smooth movement entirely free of vibration.12.4 Measure the wet film thickness in accordance with TestMethods D1212 or Practice D4414.12.5 Bake, force-dry, or air-dry the coated panel, in accor-dance with its type, in a vertical position in a dust-freeatmosphere in accordance with Specificati
45、on D3924. Measurethe dry film thickness of the coating in accordance with TestMethod D1005 or Practice D7091.12.6 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 using a faster rate ofpanel withdr
46、awal.12.7 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 isfrequently obtained. Hence, if the film
47、 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 Type and amount of thinner added as a percentage byweight or volume of the
48、 total mixed coating, if applicable,13.1.3 Temperature of coating material,13.1.4 Rate of withdrawal,13.1.5 Air temperature, relative humidity and temperatureof test panel surface at time of application, and13.1.6 Mean and range of dry film thickness values ob-tained.PRACTICE CMOTOR-DRIVEN BLADE FIL
49、MAPPLICATION14. Summary of Practice14.1 A uniform film is produced by an applicator blade thatis pushed or pulled across the test panel at a uniform speed bya motor-driven device.14.2 The wet film thickness of the coating applied may beaffected by the speed at which the applicator blade is moved,the clearance of the applicator blade, the design of theapplicator blade, and the viscosity of the coating.15. Significance and Use15.1 This test method is applicable to substrates consistingof uniform rigid materials, such as metal or glass, and ofnon-rigid materials, s
