ASTM_D_1746_-_15.pdf

Designation:D174615Standard Test Method forTransparency of Plastic Sheeting1This standard is issued under the fixed designation D1746;the number immediately following the designation indicates the year oforiginal adoption or,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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope*1.1 This test method covers the measurement of the trans-parency of plastic sheeting in terms of regular transmittance(Tr).Although generally applicable to any translucent ortransparent material,it is principally intended for use withnominally clear and colorless thin sheeting.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.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 practices and determine the applica-bility of regulatory limitations prior to use.NOTE1There is no known ISO equivalent to this standard.NOTE2For additional information,see Terminology E284 and Prac-tice E1164.2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD1003 Test Method for Haze and Luminous Transmittanceof Transparent PlasticsE284 Terminology of AppearanceE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1164 Practice for Obtaining Spectrometric Data for Object-Color EvaluationE1316 Terminology for Nondestructive ExaminationsE1345 Practice for Reducing the Effect of Variability ofColor Measurement by Use of Multiple MeasurementsE1347 Test Method for Color and Color-Difference Mea-surement by Tristimulus ColorimetryE1348 Test Method for Transmittance and Color by Spec-trophotometry Using Hemispherical Geometry3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method,referto Terminologies D883,E284,and E1316.4.Significance and Use4.1 The attribute of clarity of a sheet,measured by its abilityto transmit image-forming light,correlates with its regulartransmittance.Sensitivity to differences improves with de-creasing incident beam-and receptor-angle.If the angularwidth of the incident beam and of the receptor aperture(as seenfrom the specimen position)are of the order of 0.1 or less,sheeting of commercial interest have a range of transparency ofabout 10 to 90%as measured by this test.Results obtained bythe use of this test method are greatly influenced by the designparameters of the instruments;for example,the resolution islargely determined by the angular width of the receptoraperture.Caution should therefore be exercised in comparingresults obtained from different instruments,especially forsamples with low regular transmittance.4.2 Regular transmittance data in accordance with this testmethod correlate with the property commonly known as“see-through,”which is rated subjectively by the effect of ahand-held specimen on an observers ability to distinguishclearly a relatively distant target.This correlation is poor forhighly diffusing materials because of interference of scatteredlight in the visual test.5.Apparatus5.1 The apparatus shall consist of a light source,sourceaperture,lens system,specimen holder,receptor aperture,photoelectric detector,and an indicating or recording system,arranged to measure regular transmittance.The system shallmeet the following requirements:5.1.1 An incandescent or vapor-arc lamp,with a regulatedpower supply such that fluctuations in light intensity shall beless than 61%.If an arc lamp is used,an appropriate filtershall be used to limit light only to the spectral range from 540to 560 nm.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.40 on Optical Properties.Current edition approved April 1,2015.Published April 2015.Originallyapproved in 1960.Last previous edition approved in 2009 as D1746 09.DOI:10.1520/D1746-15.2For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.1.2 Asystem of apertures and lenses shall be used that willprovide a symmetrical incident beam.When measured with theindicating or recording system of the apparatus,using areceptor aperture having a width or diameter subtending anangle of 0.025 6 0.005 at the plane of the specimen,theincident beam shall meet the following requirem