1、Designation: D7538 09 (Reapproved 2013)Standard Practice forEvaluating the Water Wash-Off Resistance of Traffic PaintsUsing an Atomizing Spray Device1This standard is issued under the fixed designation D7538; the number immediately following the designation indicates the year oforiginal adoption or,
2、 in 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 Anewly applied traffic paint film may be exposed to rainof varying intensities s
3、hortly after application. Practice D7377describes 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 D7538 is a similar practice that describes the use of anadjustable
4、 nozzle atomizing spray device to deliver a spray ofwater that simulates rain rates from approximately 0.05 to 0.5L per min. This test can be used to compare conventional andfast-dry traffic paints for their relative ability to withstand rainsoon after application on roadway surfaces.1.2 The values
5、stated in SI units 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
6、 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D562 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 Paint
7、D823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD1212 Test Methods for Measurement of Wet Film Thick-ness of Organic CoatingsD3924 Specification
8、for Environment for Conditioning andTesting Paint, Varnish, Lacquer, and Related MaterialsD4414 Practice for Measurement of Wet Film Thickness byNotch GagesD7377 Practice for Evaluating the Water Wash-Off Resis-tance of Traffic Paints using a Water Faucet3. Terminology3.1 Definitions:3.1.1 conventio
9、nal waterborne 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 paints are20 to 45 min.3.1.2 durable fast-dry waterborne traffc paint, nan aque-ous traffic pai
10、nt that 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 s
11、tandard 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 p
12、aint, nanaqueous 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
13、 conventional 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.3.1.6.1 DiscussionSometimes referred to as water wash-out.1This practice is under the jurisdiction of ASTM Committee D01 o
14、n Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.44 on Traffic Coatings.Current edition approved Nov. 1, 2013. Published November 2013. Originallyapproved in 2009. Last previous edition approved in 2009 as D7538 09. DOI:10.1520/D7538-09R13.
15、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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C
16、700, West Conshohocken, PA 19428-2959. United States14. Summary of Practice4.1 This practice involves preparing a series 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
17、 subsequently sub-jected to a water spray. Films are wash-off resistant when nopaint is removed by the water spray.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
18、. This practice can beused to determine the relative water wash-off resistance ofwaterborne traffic paints when exposed 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
19、Room, at 23 6 2C and 50 6 5 % relativehumidity for film draw-downs and film drying.6.3 Humidity Gauge, to record relative 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-dow
20、ns (see also option forcharts in 6.7).6.7 Draw-Down Chart, preferred option for film draw-downs. Black Scrub Test Panels 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 rem
21、oval.6.8 Film Applicator (15 cm width), to obtain 0.38 mm wetthickness for standard traffic paints or 0.64 mm wet thicknessfor 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 garde
22、n-type sprayercapable of delivering a continuous spray), to provide a waterspray as described in 8.2.6.11 Graduated Cylinder 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.
23、12 Timer, to time the film-drying and the water sprayperiods.7. Reagents7.1 Tap Waterto partially fill the sprayer container.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 Kr
24、ebs (KU) viscosity of the paint inaccordance with Test Method D562 using a paddle-typeviscometer as prescribed by Test Method D562. 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 Cal
25、ibration of Atomizing Spray Devices:8.2.1 Partially fill the finger pumped, adjustable nozzlespray bottle or adjustable 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 a
26、rea from a 15 cm distance.8.2.3 For a finger pumped spray device, aim the spray intoa funnel placed in a graduated cylinder 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,
27、for a continuous spray garden-typesprayer, determine the time to deliver 25 mL of water. The timeto deliver 25 mL of 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 traffi
28、c paints or a 0.64 mmwet film thickness for durable traffic paints. This determinationshould be made in advance using Practice D823 by making aseries of draw-downs with different applicator gaps and mea-suring the wet-film thickness of each using Test Method D1212or Test Method D4414. The actual wet
29、 film thickness is oftenmuch lower than the indicated film applicator gap, for example,a 0.64 mm gap may produce a 0.38 mm wet film thickness. Dryfilm thickness can optionally be determined using Test MethodD1005. Clean glass plates with acetone, or optionally use thepreferred black draw-down charts
30、 for the film draw-downs.Place about 10 ml of paint on the top center of the glass plateor draw-down chart and drag the draw-down bar over the paintto 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 2
31、3 6 2Cand 50 6 5 % relative humidity, as defined in SpecificationD3924.8.3.3 Allow the films to dry undisturbed 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 ver
32、tical position 15 cm from the spray nozzle.8.4.2 Spray 25 mL of water by either counting the numberof finger pumps 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 o
33、ff and note the number of finger pumps ortime required to reach this point. The paint film is consideredwash-off 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.D7538
34、09 (2013)28.4.4 For clean-up of glass plates, run the plates under hotwater to loosen the film and then scrape the paint off with arazor 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 pract
35、ice:9.1.1 Viscosity of the paint in Krebs Units (KU),9.1.2 Drying conditions (temperature and humidity), wetfilm thickness, 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
36、) to deliver 23 mL of water, and9.1.4 Number of finger pumps (finger pump device) or time(continuous spray device) to first 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
37、 respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of 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.T
38、his standard is subject to revision at any time by the responsible technical committee and must be reviewed every five 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 In
39、ternational Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, 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 show
40、n 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D7538 09 (2013)3
