1、Designation: D 7538 09Standard Practice forEvaluating the Water Wash-Off Resistance of Traffic PaintsUsing an Atomizing Spray Device1This standard is issued under the fixed designation D 7538; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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 Anewly applied traffic paint film may be exposed to rainof varying intensities shortly after app
3、lication. Practice D 7377describes a practice for evaluating the water wash-off resis-tance of traffic paints to a hard rain using a steady stream ofwater from a faucet at a rate of approximately 5.7 L per min.Practice D 7538 is a similar practice that describes the use ofan adjustable nozzle atomiz
4、ing spray device to deliver a sprayof water that simulates rain rates from approximately 0.05 to0.5 L per min. This test can be used to compare conventionaland fast-dry traffic paints for their relative ability to withstandrain soon after application on roadway surfaces.1.2 The values stated in SI u
5、nits are to be regarded asstandard. No other units of measurement are included in thisstandard.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 standard to establish appro-priate safety and health pr
6、actices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 562 Test Method for Consistency of Paints MeasuringKrebs Unit (KU) Viscosity Using a Stormer-Type Viscom-eterD711 Test Method for No-Pick-Up Time of Traffic PaintD 823 Practic
7、es for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsD 1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD 1212 Test Methods for Measurement of Wet Film Thick-ness of Organic CoatingsD 3924 Specification for Envir
8、onment for Conditioning andTesting Paint, Varnish, Lacquer, and Related MaterialsD 4414 Practice for Measurement of Wet Film Thickness byNotch GagesD 7377 Practice for Evaluating the Water Wash-Off Resis-tance of Traffic Paints using a Water Faucet3. Terminology3.1 Definitions:3.1.1 conventional wat
9、erborne traffc paint, nan aqueoustraffic paint that uses a conventional-dry latex binder.3.1.1.1 DiscussionTypical no-pick-up dry times, as pre-scribed in Test Method D711, for conventional traffic paintsare 20 to 45 min.3.1.2 durable fast-dry waterborne traffc paint, nan aque-ous traffic paint that
10、 uses a third generation durable fast-drylatex binder.3.1.2.1 DiscussionAir or airless spray application onroadways is typically 0.64 mm wet or about 0.39 mm dry. Therange of application for durable waterborne paints is 0.56 to0.89 mm wet, but sometimes the durable paints are also stripedat standard
11、 line thickness.3.1.3 fast-dry waterborne traffc paint, nan aqueous trafficpaint that uses a fast-dry traffic latex binder.3.1.3.1 DiscussionTypical no-pick-up dry times, as pre-scribed in Test Method D711, for fast-dry traffic paints are 10min.3.1.4 standard line fast-dry waterborne traffc paint, n
12、anaqueous traffic paint that uses a first or second generationfast-dry latex binder.3.1.4.1 DiscussionAir or airless spray application onroadways is typically 0.38 mm wet or about 0.23 mm dry.3.1.5 waterborne traffc paint, nan aqueous traffic paint(usually white or yellow) containing either a conven
13、tional orfast-dry latex binder.3.1.6 water wash-off, nthe erosion or removal of freshlyapplied traffic paint in the field by rain or in the laboratoryusing simulated rain.1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and is t
14、he direct responsibility ofSubcommittee D01.44 on Traffic Coatings.Current edition approved June 1, 2009. Published July 2009.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
15、 refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.6.1 DiscussionSometimes referred to as water wash-out.4. Summary of Practice4.1 This practice involves preparing a s
16、eries of uniformthickness films of traffic paint on standard substrates. The filmsare allowed to dry over different time periods in a conditionedenvironment, and then each paint film is subsequently sub-jected to a water spray. Films are wash-off resistant when nopaint is removed by the water spray.
17、5. Significance and Use5.1 After waterborne traffic paints are applied to a roadpavement, it is important that they be sufficiently coalesced orcured so they will not be removed by rain. This practice can beused to determine the relative water wash-off resistance ofwaterborne traffic paints when exp
18、osed to a water spraysimulated rain.6. Apparatus and Equipment6.1 Paddle Type Viscometer, to measure viscosity (in Krebsunits) of the traffic paint prior to application.6.2 Conditioned Room,at236 2C and 50 6 5 % relativehumidity for film draw-downs and film drying.6.3 Humidity Gauge, to record relat
19、ive humidity during thedrying period.6.4 Thermometers, to record the air and water temperatures.6.5 Spatula, to mix the paint prior to application.6.6 Glass Plates, for film draw-downs (see also option forcharts in 6.7).6.7 Draw-Down Chart, preferred option for film draw-downs. Black Scrub Test Pane
20、ls are preferred and can be cut inhalf to give two test panels of 16.5 by 21.6 cm size. Use ofthese charts instead of a glass plate allows for easier visual-ization of paint film removal.6.8 Film Applicator (15 cm width), to obtain 0.38 mm wetthickness for standard traffic paints or 0.64 mm wet thic
21、knessfor durable traffic paints.6.9 Wet Film Gauge, to measure wet film thickness.6.10 Atomizing Spray Device (finger pumped, adjustablenozzle spray bottle or adjustable nozzle garden-type sprayercapable of delivering a continuous spray), to provide a waterspray as described in 8.2.6.11 Graduated Cy
22、linder and Funnel or Beaker, to deter-mine the number of finger pumps (finger pumped spray device)or the time (continuous garden-type spray device) required tospray 25 mL of water.6.12 Timer, to time the film-drying and the water sprayperiods.7. Reagents7.1 Tap Waterto partially fill the sprayer con
23、tainer.7.2 Acetoneto clean glass plates prior to paint application(not needed for draw-down charts since they are not reused.)8. Procedure8.1 Paint Consistency:8.1.1 Determine the Krebs (KU) viscosity of the paint inaccordance with Test Method D 562 using a paddle-typeviscometer as prescribed by Tes
24、t Method D 562. This determi-nation is optional but can be important since the dry time of thetraffic paint and water-wash off performance can be affected bythe paint viscosity.8.2 Calibration of Atomizing Spray Devices:8.2.1 Partially fill the finger pumped, adjustable nozzlespray bottle or adjusta
25、ble nozzle garden-type sprayer with atleast 250 mL of clean tap water and allow to equilibrate toroom temperature.8.2.2 Adjust the spray nozzle to deliver a 10 to 15 cmdiameter spray area from a 15 cm distance.8.2.3 For a finger pumped spray device, aim the spray intoa funnel placed in a graduated c
26、ylinder or into a beaker todetermine the number of finger pumps required to deliver 25mL of water. The time to deliver 25 mL of water should bebetween 15 and 30 s.8.2.4 Alternatively, for a continuous spray garden-typesprayer, determine the time to deliver 25 mL of water. The timeto deliver 25 mL of
27、 water should be between 5 and 10 s.8.3 Application and Conditioning of Paint Films:8.3.1 Select the appropriate draw-down bar to obtain a 0.38mm wet film thickness for standard traffic paints or a 0.64 mmwet film thickness for durable traffic paints. This determinationshould be made in advance usin
28、g Practice D 823 by making aseries of draw-downs with different applicator gaps and mea-suring the wet-film thickness of each using Test MethodD 1212 or Test Method D 4414. The actual wet film thicknessis often much lower than the indicated film applicator gap, forexample, a 0.64 mm gap may produce
29、a 0.38 mm wet filmthickness. Dry film thickness can optionally be determinedusing Test Method D 1005. Clean glass plates with acetone, oroptionally use the preferred black draw-down charts for thefilm draw-downs. Place about 10 ml of paint on the top centerof the glass plate or draw-down chart and d
30、rag the draw-downbar over the paint to produce a coating of uniform thickness.8.3.2 Immediately start a timer for each film drawn-downand place each coated panel in a conditioned room at 23 6 2Cand 50 6 5 % relative humidity, as defined in SpecificationD 3924.8.3.3 Allow the films to dry undisturbed
31、 for a set timeperiod. Dry time intervals of 15, 30, 45 and 60 min. aresuggested.8.4 Water Wash-Off Test:8.4.1 After the designated dry time interval, hold or affix thecoated panel in a vertical position 15 cm from the spray nozzle.8.4.2 Spray 25 mL of water by either counting the numberof finger pu
32、mps or time interval as determined in the calibra-tion procedure for the two types of spray devices (8.2.3).8.4.3 Watch at the bottom of the panel for the first indicationof paint washing off and note the number of finger pumps ortime required to reach this point. The paint film is consideredwash-of
33、f resistant when no paint is visibly washed down fromthe test area. Black substrates such as black vinyl draw-downcharts are particularly useful for seeing and rating wash-offfailure.8.4.4 For clean-up of glass plates, run the plates under hotwater to loosen the film and then scrape the paint off wi
34、th aD7538092razor blade scraper. The draw-down charts can simply bediscarded or retained for visual record.9. Report9.1 The following ideally should be recorded when usingthis practice:9.1.1 Viscosity of the paint in Krebs Units (KU),9.1.2 Drying conditions (temperature and humidity), wetfilm thickn
35、ess, and dry time intervals for each draw-down,9.1.3 Atomizing spray device used, distance to panel, andnumber of finger pumps (finger pump device) or time (con-tinuous spray device) to deliver 23 mL of water, and9.1.4 Number of finger pumps (finger pump device) or time(continuous spray device) to f
36、irst indication of wash-off failureat each drying time interval.10. Keywords10.1 rain resistance; traffic paint; water spray; water wash-off testASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of
37、this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five
38、years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical com
39、mittee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D7538093
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