1、Designation:D 3793 04Standard Test Method forLow-Temperature Coalescence of Latex Paint Films1This standard is issued under the fixed designation D 3793;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A numb
2、er 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 the determination of the com-parative coalescence of a series of latex paints by determiningthe porosity of films drie
3、d at standard and at low temperature.Porosity is evaluated with a penetrating medium as in TestMethod D 3258.1.2 The texture of the film,which can affect cleanup,willinfluence the results of the test.Stain applied to a high-hidingpaint will not lower the reflectance as much as the same stainapplied
4、to a low-hiding paint of equal porosity.These pointsmust be considered in comparing the different paints.1.3 This method should be used only for comparativetesting within one laboratory,as the numerical results obtainedby different laboratories do not usually agree.1.4 The values stated in SI units
5、are to be regarded as thestandard.The values given in parentheses are for informationonly.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
6、and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D 3258 Test Method for Porosity of White or Near WhitePaint Films by StainingE 1347 Test Method for Color and Color Difference Mea-surement of Object-Color Specimens by Tristimulus(Fil-t
7、er)Colorimetry3.Summary of Test Method3.1 The test paints are applied to porous cardboard panels,dried at standard temperature and at 4.5C(40F)with 50%relative humidity in both cases,and their reflectances mea-sured.Aspecial colored penetrating medium is applied to each,the excess removed in a speci
8、fied manner,and reflectancesmeasured again.The difference between the readings on thestained and unstained films indicates the porosity of that film;the difference between the readings for the two temperaturesindicates the coalescence of that film compared to others in theseries.4.Significance and U
9、se4.1 This test method provides no absolute information,rather ranking only of the selected series of paints.4.2 This test method can provide a pass-fail situation ifknown acceptable and unacceptable paints are included in thetest.5.Apparatus and Materials5.1 Plate Glass Panel(base for cardboard pan
10、el).5.2 Strippable Adhesive.35.3 Test PanelSmooth porous cardboard pane,such as theback of a white drawdown chart.45.4 Film Applicator,150 mm(6 in.)wide with a clearanceof 150 m(6 mils).NOTE1It should be noted that some applicators are marked with thenominal wet film thickness,which is one half of t
11、he clearance.5.5 Film Applicator,140 mm(512in.)wide with a clearanceof 255 m(10 mils).55.6 Reflectometer,meeting the requirements of Test MethodE 1347.5.7 Cold Cabinet,maintaining 4.5 6 1C(40 6 2F)and50 6 5%relative humidity.5.8 Camels Hair Brush,approximately 13 mm(12in.)wide.5.9 Plastic Wash Bottl
12、e,about 500 mL or 16 oz containingmineral spirits of the odorless type.5.10 Penetrating MediumA proprietary composition ofpigments or dye,or both,dispersed in a liquid vehicle.5.11 Filter Paper.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,a
13、nd Applications and is the direct responsibility ofSubcommittee D01.42 on Architectural Coatings.Current edition approved June 1,2004.Published July 2004.Originally approvedin 1979.Last previous edition approved in 2000 as D 3793 00.2For referenced ASTM standards,visit the ASTM website,www.astm.org,
14、orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Any strippable adhesive such as represented by the following formulas:vinylacrylic emulsion(800 parts by weight)and polyethylene gly
15、col,molecular weight1450,(16 parts by weight).4White cardboard drawdown chart,Form WA,from the Leneta Co.,15 WhitneyRd.,Mahwah,NJ 07430,was used in the original test method to get the results.5The Dow latex film caster from Byk-Gardner,Inc.Gardner Laboratory,2435Linden Lane,Silver Spring,MD 20910,wa
16、s used originally in this test method.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.6.Procedure6.1 Adhere a porous cardboard test panel to each of as manyplate glass panels as needed,using the strippable adhesive andensuring that the cardboard panels are smooth with nowrinkles.6.2 For each paint,coat one panel using the 150-m(6-mil)clearance drawdown blade.Air dry 48 h under standardconditions of 23 6 2C(73.5 6 3.5F)and 50 6 5%relat