1、Designation: D2457 081Standard Test Method forSpecular Gloss of Plastic Films and Solid Plastics1This standard is issued under the fixed designation D2457; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、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 Department of Defense.1NOTEAdded research report information to Section 11 editorially
3、 in September 2010.1. Scope*1.1 This test method describes procedures for the measure-ment of gloss of plastic films and solid plastics, both opaqueand transparent. It contains four separate gloss angles (Note 1):1.1.1 60-deg, recommended for intermediate-gloss films,1.1.2 20-deg, recommended for hi
4、gh-gloss films,1.1.3 45-deg, recommended for intermediate and low-glossfilms, and1.1.4 75-deg, recommended for plastic siding and soffit.NOTE 1The 75-deg, 60-deg, and 20-deg apparatus and method ofmeasurement duplicate those in Test Method D523; those for the 45procedure are similarly taken from Tes
5、t Method C346.1.2 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.N
6、OTE 2There is no similar or equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:2C346 Test Method for 45-deg Specular Gloss of CeramicMaterialsD523 Test Method for Specular GlossE284 Terminology of AppearanceE691 Practice for Conducting an Interlaboratory Study toDetermine the Precisio
7、n of a Test MethodE1347 Test Method for Color and Color-Difference Mea-surement by Tristimulus ColorimetryE1349 Test Method for Reflectance Factor and Color bySpectrophotometry Using Bidirectional (45:0 or 0:45)Geometry3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, se
8、e Terminology E284.4. Significance and Use4.1 Specular gloss is used primarily as a measure of theshiny appearance of films and surfaces. Precise comparisons ofgloss values are meaningful only when they refer to the samemeasurement procedure and same general type of material. Inparticular, gloss val
9、ues for transparent films should not becompared with those for opaque films, and vice versa. Gloss isa complex attribute of a surface which cannot be completelymeasured by any single number.4.2 Specular gloss usually varies with surface smoothnessand flatness. It is sometimes used for comparative me
10、asure-ments of these surface properties.5. Apparatus5.1 Instrumental ComponentsEach apparatus (Note 3)shall consist of an incandescent light source furnishing anincident beam, means for locating the surface of the specimen,and a receptor located to receive the required pyramid of raysreflected by th
11、e specimen. The receptor shall be a photosensi-tive device responding to visible radiation.NOTE 3The 75-, 60-, and 20-deg procedures require apparatus iden-tical to that specified in Test Method D523. The 45 procedure requiresapparatus like that specified in Test Method C346.5.2 Geometric Conditions
12、The axis of the incident beamshall be at one of the specified angles from the perpendicular tothe specimen surface. The axis of the receptor shall be at themirror reflection of the axis of the incident beam. With a flatpiece of polished black glass or other front-surface mirror inspecimen position,
13、an image of the source shall be formed atthe center of the receptor field stop (receptor window). Thelength of the illuminated area of the specimen shall be equal tonot more than one third of the distance from the center of thisarea to the receptor field stop. The angular dimensions and1This test me
14、thod is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.40 on Optical Properties.Current edition approved March 1, 2008. Published March 2008. Originallyapproved in 1965. Last previous edition approved in 2003 as D2457 03. DOI:10.1520/D245
15、7-08E01.2For 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.1*A Summary of Changes section appears at the end of
16、this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.tolerances of the geometry of the source and receptor shall beas indicated in Table 1. The angular dimensions of the receptorfield stop are measured from the center of the
17、test surface. Theangular dimensions of the source field stop are mostly easilymeasured by the specimen-to-window angular size of themirror image of the source formed in the receptor field stop.(See Fig. 1 for a generalized illustration of the dimensions.)The tolerances are chosen so that errors of n
18、o more than onegloss unit at any point on the scale will result from errors in thesource and receptor aperture.5.3 VignettingThere shall be no vignetting of rays that liewithin the field angles specified in 5.2.5.4 Spectral ConditionsResults should not differ signifi-cantly from those obtained with
19、a source-filter-photocell com-bination that is spectrally corrected to yield CIE luminousefficiency with CIE Source C. Since specular reflection is, ingeneral, spectrally nonselective, spectral corrections need beapplied only to highly chromatic, low-gloss specimens uponagreement of users of this te
20、st method.5.5 Measurement MechanismThe receptor-measurementmechanism shall give a numerical indication that is propor-tional to the light flux passing the receptor field stop within 61percent of full-scale reading.6. Reference Standards6.1 Primary Working Standards may be highly polished,plane, blac
21、k glass surfaces. The specular reflectance, in per-cent, (Rs) of such surfaces shall be computed by the followingequation:Rspercent! 550FFcos i 2 =n22 sin2icos i 1 =n22 sin2iG21Fn2cos i 2 =n22 sin2in2cos i 1 =n22 sin2iG2G(1)where:i = the specular (incidence) angle, andn = the index of refraction of
22、the surface.Multiply the computed Rsat each angle by the scale factorsshown in Table 2.NOTE 4On the 45 and 60 scales, a perfect mirror measures 1000.6.2 Secondary Working Standards of ceramic tile, glass,porcelain enamel, or other materials having hard, flat, anduniform surfaces may be calibrated fr
23、om the primary standardon a glossmeter determined to be in strict conformance with therequirements prescribed in 5.2.7. Preparation and Selection of Test Specimens7.1 This test method does not cover preparation techniques.Whenever a test for gloss requires the preparation of a testspecimen, report t
24、he technique of specimen preparation.7.2 Test results have been found to be seriously affected bysurface warpage, waviness, or curvature. Ensure that specimensurfaces have good planarity. Perform tests with the directionsof machine marks, or similar texture effects, both parallel andperpendicular to
25、 the plane of the axes of the incident andreflected beams, unless otherwise specified. (Note that thisdoes not avoid the second-surface reflection.)7.3 Surface test areas shall be kept free of soil and abrasion.Gloss is due chiefly to reflection at the surface; therefore,anything that changes the su
26、rface physically or chemically islikely to affect gloss.8. Mounting Films for Measurement8.1 Any nonrigid film must be mounted in a device that willhold it flat, but will not stretch the film while it is measured.Three different filmholding devices have each proved satisfac-tory for at least some ty
27、pes of films:8.1.1 Vacuum Plate (see Fig. 2) is required for stiff films.Connect the vacuum plate by rubber tube to a vacuum pump orvacuum line. With thin, soft films it is sometimes necessary touse a valve and pressure gage and to limit the vacuum so as tokeep from collapsing the soft film into the
28、 pores of the groundplate.8.1.2 Flat Plate with two-side pressure-sensitive tape (seeFig. 3). Make sure each specimen is pulled smooth, but notstretched before holding it by the two strips of adhesive tape.Replace the tape whenever it loses its adhesiveness.8.1.3 Telescoping Ring or Hoop (see Fig. 4
29、)To mount thespecimen in the telescoping ring, lay the flexible film over thebase (male) section and drop the top over the base. Push downcarefully, taking care to pull the test film taut without stretchingit. Measure the taut area.8.2 Backing for Films That Transmit LightA matt blackbacking or (eve
30、n better) a black cavity must be placed behindany film that transmits light. Erroneous measurements willoccur without a suitable trap or backing.9. Procedure9.1 Operate the glossmeter in accordance with the manufac-turers instructions.9.2 Calibrate the instrument at the start and completion ofevery
31、period of glossmeter operation and during the operationat sufficiently frequent intervals to assure that the instrumentresponse is practically constant. If at any time an instrumentfails to repeat readings of the standard to within 2 percent ofTABLE 1 Angular Dimensions and Tolerances of Geometry of
32、 Source and Receptor Field StopsSource Field Stop Receptor Field StopGeometry, deg Incidence Angle, degIn Plane of Measurement,degPerpendicular to Plane ofMeasurement, degIn Plane of Measurement, degPerpendicular to Plane ofMeasurement, deg75 75 6 0.1 3.0 max60 60 6 0.1 0.75 6 0.25 3.0 max 4.4 6 0.1
33、 11.7 6 0.220 20 6 0.1 0.75 6 0.25 3.0 max 1.80 6 0.05 3.6 6 0.145 45 6 0.1 1.4 6 0.4 3.0 6 1.0 8.0 6 0.1 10.0 6 0.2D2457 0812the prior setting, the intervening results should be rejected. Tocalibrate, adjust the instrument to read correctly the gloss of ahighly polished standard, and then read the
34、gloss of a standardhaving poorer image-forming characteristics. If the instrumentreading for the second standard does not agree within 1 percentof its assigned value, do not use the instrument withoutreadjustment, preferably by the manufacturer.NOTE 5Correct readings on black-glass and intermediate
35、standards donot guarantee instrument conformity to specification requirements. Inaddition to measurements with gloss standards, dimensional checks forconformity to the geometric requirements of 4.2 should be made.9.3 Reduction of Amplification to Read over 100 GlossFilms on 0 to 100 Gloss ScaleA sin
36、gle smooth surface withrefractive index of 1.567 measures 100 on both the 60 and20-deg scales. Clear plastic films have two specularly reflect-ing surfaces. Even though they are less than perfectly smoothand less than 1.567 in refractive index, adding the reflectionsfrom the two surfaces frequently
37、leads to gloss values of morethan 100. If these gloss values are off-scale on the glossmeterused, recalibrate the instrument with the reading of the primaryFIG. 1 Diagram of Glossmeter Showing Essential Components and DimensionsTABLE 2 Scale Factors for Gloss Standards, Perfect Mirror and Perfect Ma
38、tt WhiteAGeometryScale Factors (multiplyRsof black glassstandard by)Value for Black Glass whenn = 1.540Value for Perfect Mirror Value for Perfect Matt White60 10.0 95.8 1000 2.120 20.3 92.3 2030 1.445 10.0 55.9 1000 5.4AThe latter are useful for estimating corrections to gloss readings for reflectio
39、n from sample backing (see Note 6).FIG. 2 Vacuum Plate Used to Hold Films FlatD2457 0813gloss standard set to a smaller value f (such as f = 50) andcorrect the gloss readings by multiplying them by (100/f).9.4 Position each specimen (mounted in a holder in the caseof films) in turn beneath (or on) t
40、he glossmeter. For specimenswith extrusion lines or other direction texture effects, orient themarks both parallel and perpendicular to the plane of the axesof the incident and reflected beams. Measure at least threeportions of the specimen surface in each direction to obtain anindication of uniform
41、ity. If no directionality is detected in thespecimen, then the test may be performed only in the parallelor perpendicular orientation.NOTE 6In the case of films, it is often desirable to compare thesereadings with readings taken across the machine direction. Difference inthe readings will relate to
42、the prominence of the machine marks.10. Report10.1 Report the following information:10.1.1 Type of specimen, its gloss (mean of three readingsfor each direction or mean of both directions), nominalthickness, whether transparent, and the specimen holder em-ployed if specimen is a film.10.1.2 All indi
43、vidual gloss readings for a specimen shall bereported if any of the gloss readings differ by more than 10 %from the average for that specimen.10.1.3 Where preparation of the test specimen has beennecessary, description or identification of the method of prepa-ration,10.1.4 Identification of the glos
44、smeter by the manufactur-ers name and model designation, and10.1.5 Identification of the working standard or standards ofgloss used.NOTE 7Diffuse CorrectionIt can be said that the light reflected bya specimen may be divided into one part reflected specularly in thedirection of mirror reflection (ass
45、ociated with gloss) and another partreflected diffusely in all directions (associated with lightness on thewhite-gray-black scale). According to this picture, a gloss reading alwaysneeds to be diminished to compensate for that amount of the measuredlight attributable to diffuse reflectance. Although
46、 it is seldom possible inpractice to analyze reflected light according to this picture and say exactlywhat part is diffuse and what part is specular, it is nevertheless frequentpractice where gloss values of light and dark surfaces are being comparedto “correct” (diminish) specular gloss settings fo
47、r diffuse reflectance. Ifdiffuse corrections are desired as additional information, measure 45-deg,0-deg luminous directional reflectances of specimens in accordance withTest Methods E1347 or E1349. Multiply reflectance values in percentageby the following factors3for diffuse corrections in gloss un
48、its:60-deg 0.02120-deg 0.01345-deg 0.05511. Precision and Bias411.1 Table 3, Table 4 and Table 5 are based on a round robinconducted in 1987 and 1988 per Practice E691 involving seventest samples. The test results in Table 3 were from 13 labs;Table 4 from seven labs and Table 5 from five labs. For e
49、achmaterial, all samples were from a single roll of film or a singleinjection molding run. Each lab obtained two test results onseparate days for each material.11.2 Table 6 is based on a round robin conducted in 2006 inaccordance with Practice E691 involving four test samples.The test results in Table 6 were from six labs. Each sample wasan extruded piece of vinyl siding from a commercial extrusionline. Each lab measured the gloss three times per sample.3Taken from Test Methods D523 and C346.4Supporting data have been filed at ASTM International
