1、Designation: D2457 081D2457 13Standard 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 re
2、vision. 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.1 NOTEAdded research report information to Section 11 ed
3、itorially in September 2010.1. Scope*1.1 This test method describes procedures for the measurement of gloss of plastic films and solid plastics, both opaque andtransparent. It contains four separate gloss angles (Note 1):1.1.1 60-deg, recommended for intermediate-gloss films,1.1.2 20-deg, recommende
4、d for high-gloss films,1.1.3 45-deg, recommended for intermediate and low-gloss films, and1.1.4 85-deg, recommended for intermediate and low gloss films, and1.1.5 75-deg, recommended for plastic siding and soffit.NOTE 1The 85-deg, 75-deg, 60-deg, and 20-deg apparatus and method of measurement duplic
5、ate those in Test Method D523 and D3679; those forthe 45 procedure are similarly taken from Test Method C346.1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety
6、 and health practices and determine the applicability of regulatorylimitations prior to use.NOTE 2There is no similar or equivalent ISO known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2C346 Test Method for 45-deg Specular Gloss of Ceramic MaterialsD523 Test Method for
7、 Specular GlossD3679 Specification for Rigid Poly(Vinyl Chloride) (PVC) SidingE284 Terminology of AppearanceE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE1347 Test Method for Color and Color-Difference Measurement by Tristimulus ColorimetryE1349 Te
8、st Method for Reflectance Factor and Color by Spectrophotometry Using Bidirectional (45:0 or 0:45) Geometry3. Terminology3.1 DefinitionsFor definitions of terms used in this test method, see Terminology E284.4. Significance and Use4.1 Specular gloss is used primarily as a measure of the shiny appear
9、ance of films and surfaces. Precise comparisons of glossvalues are meaningful only when they refer to the same measurement procedure and same general type of material. In particular,gloss values for transparent films should not be compared with those for opaque films, and vice versa. Gloss is a comp
10、lex attributeof a surface which cannot be completely measured by any single number.4.2 Specular gloss usually varies with surface smoothness and flatness. It is sometimes used for comparative measurements ofthese surface properties.1 This test method is under the jurisdiction of ASTM Committee D20 o
11、n Plastics and is the direct responsibility of Subcommittee D20.40 on Optical Properties.Current edition approved March 1, 2008April 1, 2013. Published March 2008April 2013. Originally approved in 1965. Last previous edition approved in 20032008 asD2457 03.D2457 081. DOI: 10.1520/D2457-08E01.10.1520
12、/D2457-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intend
13、ed only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current
14、 versionof the standard as published by ASTM is to be considered the official document.*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 States15. Apparatus5.1 Instrumental Compo
15、nentsEach apparatus (Note 3) shall consist of an incandescent light source furnishing an incidentbeam, means for locating the surface of the specimen, and a receptor located to receive the required pyramid of rays reflected bythe specimen. The receptor shall be a photosensitive device responding to
16、visible radiation.NOTE 3The 75-, 60-, and 20-deg procedures require apparatus identical to that specified in Test Method D523. The 45 procedure requires apparatuslike that specified in Test Method C346.5.2 Geometric ConditionsThe axis of the incident beam shall be at one of the specified angles from
17、 the perpendicular to thespecimen surface. The axis of the receptor shall be at the mirror reflection of the axis of the incident beam. With a flat piece ofpolished black glass or other front-surface mirror in specimen position, an image of the source shall be formed at the center of thereceptor fie
18、ld stop (receptor window). The length of the illuminated area of the specimen shall be equal to not more than one thirdof the distance from the center of this area to the receptor field stop. The angular dimensions and tolerances of the geometry ofthe source and receptor shall be as indicated in Tab
19、le 1. The angular dimensions of the receptor field stop are measured from thecenter of the test surface. The angular dimensions of the source field stop are mostly easily measured by the specimen-to-windowangular size of the mirror image of the source formed in the receptor field stop. (See Fig. 1 f
20、or a generalized illustration of thedimensions.) The tolerances are chosen so that errors of no more than one gloss unit at any point on the scale will result from errorsin the source and receptor aperture.5.3 VignettingThere shall be no vignetting of rays that lie within the field angles specified
21、in 5.2.5.4 Spectral ConditionsResults should not differ significantly from those obtained with a source-filter-photocell combinationthat is spectrally corrected to yield CIE luminous efficiency with CIE Source C. Since specular reflection is, in general, spectrallynonselective, spectral corrections
22、need be applied only to highly chromatic, low-gloss specimens upon agreement of users of thistest method.5.5 Measurement MechanismThe receptor-measurement mechanism shall give a numerical indication that is proportional tothe light flux passing the receptor field stop within 61 percent of full-scale
23、 reading.6. Reference Standards6.1 Primary Working Standards may be highly polished, plane, black glass surfaces. The specular reflectance, in percent, (Rs)of such surfaces shall be computed by the following equation:Rs percent!5 (1)50 FF cos i 2=n2 2 sin 2 icos i1=n 2 2 sin 2 i G21Fn2 cosi 2=n 2 2
24、sin 2 in 2 cosi1=n 2 2 sin 2 i G2 Gwhere:i = the specular (incidence) angle, andn = the index of refraction of the surface.Multiply the computed Rs at each angle by the scale factors shown in Table 2.NOTE 4On the 45 and 60 scales, a perfect mirror measures 1000.6.2 Secondary Working Standards of cer
25、amic tile, glass, porcelain enamel, or other materials having hard, flat, and uniformsurfaces may be calibrated from the primary standard on a glossmeter determined to be in strict conformance with the requirementsprescribed in 5.2.7. Preparation and Selection of Test Specimens7.1 This test method d
26、oes not cover preparation techniques. Whenever a test for gloss requires the preparation of a testspecimen, report the technique of specimen preparation.TABLE 1 Angular Dimensions and Tolerances of Geometry of Source and Receptor Field StopsSource Field Stop Receptor Field StopGeometry, deg Incidenc
27、e Angle, deg In Plane of Measurement,deg Perpendicular to Plane ofMeasurement, deg In Plane of Measurement, deg Perpendicular to Plane ofMeasurement, deg75 75 0.1 3.0 max60 60 0.1 0.75 0.25 3.0 max 4.4 0.1 11.7 0.220 20 0.1 0.75 0.25 3.0 max 1.80 0.05 3.6 0.145 45 0.1 1.4 0.4 3.0 1.0 8.0 0.1 10.0 0.
28、2D2457 1327.2 Test results have been found to be seriously affected by surface warpage, waviness, or curvature. Ensure that specimensurfaces have good planarity. Perform tests with the directions of machine marks, or similar texture effects, both parallel andperpendicular to the plane of the axes of
29、 the incident and reflected beams, unless otherwise specified. (Note that this does not avoidthe 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, anythingthat changes the surface physically or che
30、mically is likely to affect gloss.8. Mounting Films for Measurement8.1 Any nonrigid film must be mounted in a device that will hold it flat, but will not stretch the film while it is measured. Threedifferent filmholding devices have each proved satisfactory for at least some types of films:8.1.1 Vac
31、uum 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 to use a valve and pressure gage and to limit the vacuum so as to keepfrom collapsing the soft film into the pores of the ground
32、 plate.8.1.2 Flat Plate with two-side pressure-sensitive tape (see Fig. 3). Make sure each specimen is pulled smooth, but not stretchedbefore 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)To mount the spe
33、cimen in the telescoping ring, lay the flexible film over the base(male) section and drop the top over the base. Push down carefully, taking care to pull the test film taut without stretching it.Measure the taut area.8.2 Backing for Films That Transmit LightA matt black backing or (even better) a bl
34、ack cavity must be placed behind anyfilm that transmits light. Erroneous measurements will occur without a suitable trap or backing.9. Procedure9.1 Operate the glossmeter in accordance with the manufacturers instructions.9.2 Calibrate the instrument at the start and completion of every period of glo
35、ssmeter operation and during the operation atsufficiently frequent intervals to assure that the instrument response is practically constant. If at any time an instrument fails torepeat readings of the standard to within 2 percent of the prior setting, the intervening results should be rejected.To ca
36、librate, adjustthe instrument to read correctly the gloss of a highly polished standard, and then read the gloss of a standard having poorerimage-forming characteristics. If the instrument reading for the second standard does not agree within 1 percent of its assignedvalue, do not use the instrument
37、 without readjustment, preferably by the manufacturer.NOTE 5Correct readings on black-glass and intermediate standards do not guarantee instrument conformity to specification requirements. In additionto measurements with gloss standards, dimensional checks for conformity to the geometric requirement
38、s of 4.2 should be made.FIG. 1 Diagram of Glossmeter Showing Essential Components and DimensionsTABLE 2 Scale Factors for Gloss Standards, Perfect Mirror and Perfect Matt WhiteAGeometryScale Factors (multiplyRs of black glassstandard by)Value for Black Glass whenn = 1.540 Value for Perfect Mirror Va
39、lue for Perfect Matt White60 10.0 95.8 1000 2.120 20.3 92.3 2030 1.445 10.0 55.9 1000 5.4A The latter are useful for estimating corrections to gloss readings for reflection from sample backing (see Note 6).D2457 1339.3 Reduction of Amplification to Read over 100 Gloss Films on 0 to 100 Gloss ScaleA
40、single smooth surface with refractiveindex of 1.567 measures 100 on both the 60 and 20-deg scales. Clear plastic films have two specularly reflecting surfaces. Eventhough they are less than perfectly smooth and less than 1.567 in refractive index, adding the reflections from the two surfacesfrequent
41、ly leads to gloss values of more than 100. If these gloss values are off-scale on the glossmeter used, recalibrate theinstrument with the reading of the primary gloss standard set to a smaller value f (such as f = 50) and correct the gloss readingsby multiplying them by (100/f).FIG. 2 Vacuum Plate U
42、sed to Hold Films FlatFIG. 3 Flat Plate with Two-Sided Pressure-Sensitive Tape Used to Hold Flexible Films for Gloss MeasurementFIG. 4 Telescoping Ring Used to Hold Flexible Films for Gloss and Haze MeasurementsD2457 1349.4 Position each specimen (mounted in a holder in the case of films) in turn be
43、neath (or on) the glossmeter. For specimens withextrusion lines or other direction texture effects, orient the marks both parallel and perpendicular to the plane of the axes of theincident and reflected beams. Measure at least three portions of the specimen surface in each direction to obtain an ind
44、ication ofuniformity. If no directionality is detected in the specimen, then the test may be performed only in the parallel or perpendicularorientation.NOTE 6In the case of films, it is often desirable to compare these readings with readings taken across the machine direction. Difference in the read
45、ingswill relate to the prominence of the machine marks.10. Report10.1 Report the following information:10.1.1 Type of specimen, its gloss (mean of three readings for each direction or mean of both directions), nominal thickness,whether transparent, and the specimen holder employed if specimen is a f
46、ilm.10.1.2 All individual gloss readings for a specimen shall be reported if any of the gloss readings differ by more than 10 % fromthe average for that specimen.10.1.3 Where preparation of the test specimen has been necessary, description or identification of the method of preparation,10.1.4 Identi
47、fication of the glossmeter by the manufacturers name and model designation, and10.1.5 Identification of the working standard or standards of gloss used.NOTE 7Diffuse CorrectionIt can be said that the light reflected by a specimen may be divided into one part reflected specularly in the directionof m
48、irror reflection (associated with gloss) and another part reflected diffusely in all directions (associated with lightness on the white-gray-black scale).According to this picture, a gloss reading always needs to be diminished to compensate for that amount of the measured light attributable to diffu
49、sereflectance. Although it is seldom possible in practice to analyze reflected light according to this picture and say exactly what part is diffuse and whatpart is specular, it is nevertheless frequent practice where gloss values of light and dark surfaces are being compared to “correct” (diminish) specular glosssettings for diffuse reflectance. If diffuse corrections are desired as additional information, measure 45-deg, 0-deg luminous directional reflectances ofspecimens in accordance with Test Methods E1347 or
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