1、Designation:D 3719 00Standard Test Method forQuantifying Dirt Collection on Coated Exterior Panels1This standard is issued under the fixed designation D 3719;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A
2、 number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers an instrumental procedure forquantifying the degree of dirt collection on exposed exteriorcoated panels.1.2 This
3、test method is limited to those coated exteriorpanels with lightness values before exposure significantlygreater than those after exposure.1.3 The instrumental readings do not distinguish betweenmildew growth and other forms of dirt.1.4 This test method measures total dirt collection.Loosedirt may b
4、e washed and removed from specimens if onlyimbedded dirt collection is to be measured.1.5 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 and health practices and
5、determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 823 Practices for Producing Films of Uniform Thicknessof Paint,Varnish,and Related Products on Test Panels2D 2244 Test Method for Calculation of Color Differencesfrom Instrumentally Measure
6、d Color Coordinates2D 3274 Test Method for Evaluating Degree of SurfaceDisfigurement of Paint Films by Microbial(Fungal orAlgal)Growth or Soil and Dirt Accumulation23.Terminology3.1 Definitions:3.1.1 dirt collection,nthe collection of foreign matter thatdarkens the surface of exterior exposed coated
7、 panels.4.Summary of Test Method4.1 Lightness readings using a color difference meter aremade before and after exposure,and the difference is consid-ered to be due to dirt collection.5.Significance and Use5.1 Change in color or appearance of coated exterior sur-faces due to such factors as dirt coll
8、ection or retention isundesirable.If Test Method D 3274 or other test methods areused to establish that dirt collection is the primary cause ofsuch a change,this test method can be used to quantify thedegree of dirt collection or,more properly,the degree ofchange in visual appearance of the coated s
9、urface due to dirtcollection.5.2 When used in this manner and with color change,exposure duration and environment specified,this test methodcan provide a performance specification with respect to dirtcollection.5.3 This test is only useful as a comparative test.6.Apparatus and Materials6.1 Color Det
10、ermination Instrument,complying with TestMethod D 2244.6.2 Test Panels,of any convenient size and of substratesuitable for exterior use.7.Preparation of Test Panels7.1 Apply the material under test to the test panels inaccordance with Practices D 823,or as agreed upon betweenthe purchaser and the se
11、ller.Allow the final coat of air dryingsystems to cure for 7 days before exposure.8.Procedure8.1 Operate the color difference meter in accordance withthe manufacturers instructions.Standardize with either aprimary or working standard as defined in Test MethodD 2244.Restandardize at sufficient interv
12、als,in accordancewith the manufacturers instructions,to minimize the effects ofinstrumental drift.8.2 Determine the metric lightness,L*,in the CIE 1976L*a*b*Uniform Color Space(CIE LAB),for each unexposedpanel at three marked,random locations.Calculate the arith-metic mean,L*A.8.3 Expose the panels
13、at a 45 angle to the horizontal facingthe equator at an exterior location for 61 days.8.3.1 The calendar time,location,angle of exposure,orien-tation,exposure time,and method of exposure may be modi-fied by mutual agreement.8.4 Remove the panels and determine,using the procedure1This test method is
14、under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.52 on Factory-Coated Wood Products.Current edition approved Nov.10,2000.Published January 2000.Originallypublished as D 3719 78.Last previous editi
15、on D 3719 95.2Annual Book of ASTM Standards,Vol 06.01.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.outlined above,the light reflectance value,L*,for the exposedpanels.Calculate the arithmetic mean of the marked locations,L*B.9.Calculations9.1 Compute the dirt c
16、ollection index,Dc,as follows:Dc5L*BL*A3 100(1)where:L*A=arithmetic mean of unexposed panel values,andL*B=arithmetic mean of exposed panel values.10.Report10.1 Report the following information:10.1.1 Arithmetic mean and range of each panels Lxvalue,and whether fungal growth is included in the reading,as wellas the calculated dirt collection index.Report if the exposedpanel was washed before taking the light reflectance value.10.1.2 Any noticeable color change which,for reasons otherthan dirt acc
