1、Designation: D7539 10 (Reapproved 2015)Standard Practice forUsing a Test Chamber for Humidity Conditioning of TestPanels of Pavement Marking Paints1This standard is issued under the fixed designation D7539; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n the case of revision, 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.1. Scope1.1 Specification D3924 defines a standard environment of23 6 2C and 50 6 5 % relative
3、 humidity and free from draftsfor normal conditioning and testing of paint, varnish, lacquer,and related materials. This practice describes a test chamberthat allows for control of relative humidity above the ambientrelative humidity and minimization of air flow for conditioningof test panels at ele
4、vated relative humidity and room tempera-tures.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to
5、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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D711 Test
6、Method for No-Pick-Up Time of Traffic PaintD1640 Test Methods for Drying, Curing, or Film Formationof Organic CoatingsD3924 Specification for Environment for Conditioning andTesting Paint, Varnish, Lacquer, and Related MaterialsD7377 Practice for Evaluating the Water Wash-Off Resis-tance of Traffic
7、Paints using a Water FaucetD7538 Practice for Evaluating the Water Wash-Off Resis-tance of Traffic Paints Using an Atomizing Spray Device2.2 Other Standard:3TT-P-1952E Federal Specification for Paint, Traffic andAirfield Marking, Waterborne (10 July 2007)3. Terminology3.1 Definitions:3.1.1 test cham
8、ber, na cabinet or box, preferably made oftransparent, waterproof material, such as clear acrylic plastic,with panel supports and holes (ports) that can be partially tofully opened to mix outside ambient air with humidified air inthe chamber or some other means to provide humidified airwith minimal
9、air flow.3.1.1.1 DiscussionAlso commonly referred to as a humid-ity box or humidity chamber, as in Federal SpecificationTT-P-1952E.3.1.2 waterborne pavement marking (traffc) paint, nanaqueous paint used for marking pavements.4. Summary of Practice4.1 Atest chamber is described that allows for the co
10、ntrol ofrelative humidity above ambient relative humidity and theminimization of air flow variability at ambient room tempera-tures.5. Significance and Use5.1 The drying rate of organic coatings varies with changesin temperature, air flow, and relative humidity. In particular, thedrying rate of wate
11、rborne paints depends on the evaporation ofwater and thus is much more dependent on relative humiditythan are solvent based paints or paints that are 100 % solids.Measurement of the rate of drying of waterborne paints underambient conditions in laboratories cannot be adequately repli-cated without s
12、ome control of the drying conditions. A testchamber will be described that provides a means of controllingrelative humidity above ambient humidity and minimizing theeffects of air flow variability at ambient room temperatures. Ifdesired, the test chamber without water in it and with ventswide open c
13、an be placed in a temperature and humidity1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.44 on Traffic Coatings.Current edition approved June 1, 2015. Published June 2015. Or
14、iginallyapproved in 2010. Last previous edition approved in 2010 as D7539 10. DOI:10.1520/D753910R15.2For 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 D
15、ocument Summary page onthe ASTM website.3Available from General Services Administration, Federal Supply Service,Specification Section, Suite 8100, 470 LEnfant Plaza, SW, Washington DC 20407,http:/www.gsa.gov.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1942
16、8-2959. United States1controlled room to test dry speed at various temperatures aswell as humidity while using the chamber to minimize theeffect of air flow.5.2 This practice is particularly useful for testing the dryingrate of waterborne pavement marking (traffic) paints where fastdry at elevated a
17、mbient humidity is an important feature. Forwaterborne traffic paints, the test chamber can be used toevaluate dry to no-pick-up (Test Method D711) and waterwash-off resistance (Practices D7377 and D7538) at elevatedambient humidity.6. Apparatus and Equipment6.1 Test ChamberThe required elements of
18、the test cham-ber are listed below. (Manufacturing details and a photographof a suitable test chamber are shown in Appendix X1.)(1) Manufactured from transparent material to allow forvisual monitoring of relative humidity and dry time testprogress inside of the chamber.(2) Horizontal support for coa
19、ted test panels within thechamber that is perforated to allow circulation of humidifiedair.(3) A door in the front of the chamber for taking test panelsin and out of the chamber.(4) Control of relative humidity above the ambient relativehumidity and minimization of air flow.6.2 Hygrometerplaced in t
20、he test chamber in full view ofthe operator to monitor the relative humidity inside of thechamber. This hygrometer should be accurate within 63%relative humidity and provide a range from at least 20 to 100 %relative humidity.6.3 Thermometerto record air temperature.6.4 Anemometer/Wind Meter (optiona
21、l)to confirm air flowinside the chamber is “minimal” (below 0.02 m/s).6.5 Other apparatus and equipment specified in the chosendrying rate test procedure.7. Reagents7.1 Waterto provide humid air for mixing with ambient airin the test chamber.8. Procedure8.1 Preparation of Test Chamber Type Described
22、 inAppendix X1:8.1.1 Cover the bottom of the chamber with water or placewater soaked cloth or paper rags below the panel support withwater.8.1.2 Close all ports and the door and allow equilibration tothe maximum relative humidity allowed by the tolerances ofthe chamber.8.1.3 Establish the desired re
23、lative humidity by opening andclosing the ports on the sides of the chamber, preferably so thatthe size of the port openings are about the same on both sidesof the chamber to equalize the air circulation in the chamber.The relative humidity in the test chamber will stabilize once theport openings ar
24、e established. Occasional slight adjustments inthe side port openings may be required if the ambient humidityin the room changes significantly during testing.8.1.4 Target test relative humidity must be above the ambi-ent humidity in the room. It is best to use the chamber in aconditioned room at a c
25、ontrolled temperature (23 6 2C) andhumidity (50 6 5 % relative humidity) as described in Speci-fication D3924.8.2 Calibration and StandardizationWhen using the testchamber to determine drying rates, the initial rate test shouldinclude a reference paint of known performance to determinethe relative d
26、rying rates of test paints and to gauge the effect ofambient room temperature and relative humidity on the dryingrates for that test period.8.3 Using the Test Chamber for Determining Drying Rates:8.3.1 Prepare a test stripe as described in the chosen dryingrate procedure at the wet film thickness as
27、 specified by thatprocedure.8.3.2 Record the time of application or use a timer.8.3.3 Immediately place the panel with the wet film in thecenter of the panel support. The ports on the sides of the testchamber must be adjusted promptly and frequently to regainthe desired relative humidity within 65 %
28、 relative humidity.8.3.4 A second panel can be prepared and tested in thechamber at the same time. In order to be able to test the secondpanel after the same elapsed time as the first panel, it isnecessary to allow sufficient time between test panel prepara-tions. Record the time of application of t
29、he second panel andimmediately place the panel next to the first panel near thecenter of the panel support. Testing of more than two panels atone time will introduce more variability in results due to poorercontrol of drying conditions.8.3.5 At regular intervals, test the dry time of the test filmsi
30、n accordance with the procedures specified in Test MethodD711 (no-pick-up) and Practices D7377 and D7538 (waterwash-off resistance) or other desired method. All interestedparties shall agree on the time intervals at which panels areremoved from the chamber for testing.9. Report9.1 Report the relativ
31、e humidity and temperature inside thetest chamber and relative humidity outside of the test chamber.10. Keywords10.1 drying rate or drying time; dry through; no-pick-up;relative humidity; test chamber; washout resistance; water-borne traffic paintD7539 10 (2015)2APPENDIXES(Nonmandatory Information)X
32、1. TEST CHAMBER CONSTRUCTION ( see Fig. X1.1 for example)X1.1 The test chamber shall consist of a basic box, aperforated panel support, a waterproof bottom to hold water orsome other means to provide saturated air inside the chamber,and holes (ports) that can be opened partially to fully to allowamb
33、ient air to mix with the saturated air or some other meansto allow the operator to control the relative humidity inside ofthe chamber.X1.2 Place the hygrometer in the chamber so that it is in fullview of the operator. This hygrometer should be accuratewithin 63 % relative humidity and provide a rang
34、e from atleast 20 to 100 % relative humidity.X1.3 The chamber should be made of a transparent, water-proof material such as clear acrylic plastic. The clear plasticshould be38 in. thick. The joints should be water tight.X1.4 The panel support and any interior parts should bemade of corrosion-resista
35、nt materials.X2. TYPES OF CONSTRUCTIONX2.1 Fig. X2.1 (1a and 1b) are typical engineering drawingsfor front and side views of a suitable test chamber.FIG. X1.1 Test ChamberD7539 10 (2015)3FIG. X2.1 Testing Chamber Drawing Figure 1aD7539 10 (2015)4FIG. X2.1 Testing Chamber Drawing Figure 1b (continued
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