1、Designation: D 589 97 (Reapproved 2002)An American National StandardStandard Test Method forOpacity of Paper (15 Diffuse Illuminant A, 89 % ReflectanceBacking and Paper Backing)1This standard is issued under the fixed designation D 589; the number immediately following the designation indicates the
2、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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the op
3、acityof paper.1.2 Two different types of “white” backing are specified,leading to two different opacity values, in accordance withSection 3.1.3 This test method employs 15 diffuse geometry, Illumi-nant A/2 and 89 % reflectance backing or paper backing. Forthe measurement of opacity with d/0 geometry
4、, IlluminantC/2 and paper backing (see TAPPI T 519).1.4 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
5、 regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 585 Practice for Sampling and Accepting a Single Lot ofPaper, Paperboard, Fiberboard, and Related Product2D 646 Test Method for Grammage of Paper and Paperboard(Mass Per Unit Area)2D 685 Practice for Conditioning Paper
6、and Paper Productsfor Testing2D 1968 Terminology Relating to Paper and Paper Products2E 122 Practice for Calculating Sample Size to Estimate,with a Specified Tolerable Error, the Average for Charac-teristic of a Lot or Process3E 308 Practice for Computing the Colors of Objects byUsing the CIE System
7、42.2 TAPPI Standards:TAPPI Technical Information Sheet 0804-03Interrelationof reflectance, R0; reflectivity, R; TAPPI opacity, C0.89scattering, s; and absorption, k5TAPPI Technical Information Sheet 0804-06Photometriclinearity of optical properties instruments5T 519 Diffuse opacity of paper (d/0 pap
8、er backing)5T 1206 Precision statement for test methods53. Terminology3.1 Definitions: Definitions:3.1.1 Definitions shall be in accordance with Terminology D1968 and the Dictionary of Paper.53.2 Definitions of Terms Specific to This Standard:3.2.1 opacity (89 % reflectance backing), C0.89one hun-dr
9、ed times the ratio of the diffuse reflectance, R0, of a specimenbacked by a black body of 0.5 % reflectance or less to thediffuse reflectance, R0.89, of the same specimen backed with awhite body having an absolute reflectance of 0.89; thus,C0.89= 100 R0/ R0.89. Accordingly, the contrast ratio is 100
10、 %for perfectly opaque paper and is only a few percent forperfectly transparent sheets. (Sometimes called contrast ratio.)4. Summary of Test Method4.1 The reflectance of paper when combined with a whitebacking is higher than that of paper when combined with ablack backing because in the former case,
11、 light transmittedthrough the imperfectly opaque sheet is largely reflected by thewhite backing, and a portion of the light thus reflected istransmitted through the paper a second time. Two types of“white” backing are used, leading to the two measurements ofopacity defined in Section 3.5. Significan
12、ce and Use5.1 Opacity is a fundamental optical property of paper as awhole, yet the measurement of opacity is empirical. Theopacity of the sheet is influenced by the amount and kind offiller, degree of bleaching of the fibers, coating, and the like.The utility of bond, writing, and book papers may b
13、e enhancedby a high opacity.1This test method is under the jurisdiction of ASTM Committee D06 on Paperand Paper Products and is the direct responsibility of Subcommittee D06.92 on TestMethods.Current edition approved Dec.10, 1997. Published November 1998. Originallyapproved in 1940. Last previous ed
14、ition approved in 1994 as D 589 94.2Annual Book of ASTM Standards, Vol 15.09.3Annual Book of ASTM Standards, Vol 14.02.4Annual Book of ASTM Standards, Vol 06.01.5Available from the Technical Association of the Pulp and Paper Industry,Technology Park/Atlanta, P.O. Box 105113, Atlanta, GA 30348.1Copyr
15、ight ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 The determination of opacity is of vital importance toboth the manufacturer and the consumer. When white pigmentis added to a sheet, it scatters more light, and thus increasesopacity; how
16、ever, it is also possible to increase opacity of asheet by adding dark pigment or dye which absorbs light. Thisbeing so, it is of value to the manufacturer, in meeting anopacity specification, to be able to predict whether a sheetwhich does not have desired opacity can be brought up tospecification
17、by raising or, alternatively, lowering the reflec-tivity within permissible limits. To the consumer, opacitymeasurements are used to evaluate some of the characteristicsof appearance. The user is interested in the comparison ofsamples under identical conditions. When comparisons aremade, one sample
18、with another, very small differences can beidentified visually. For this reason, small measured differencesbetween similar samples represent actual differences in appear-ance.6. Apparatus6.1 Opacity Meter, equipped with an accurate linear or acorrected photometric system. The reflectance involved in
19、 thedetermination of contrast ratio should be for either normalillumination and diffuse viewing, or the equivalent converse,that is, diffuse illumination and normal viewing.NOTE 1The direction of illumination or, alternatively, the direction ofviewing, should be 15 6 2 from the normal. The instrumen
20、t may bedesigned to measure directly the ratio of reflectance of paper backed byblack and white, or, alternatively, the instrument may be adjusted toindicate a cardinal value such as 100.0 with the white backing in place,and then the ratio of reflectances is obtained by replacing the white bodywith
21、the black body. The photometric system must be sufficiently stablethat the instrument will not fluctuate by more than approximately 0.1 % ofthe full-scale deflection while the contrast ratio is being measured.6.2 The more important requirements of the apparatus are asfollows:6.2.1 Standard Black Bac
22、king, consisting of a cavity linedwith black or velvet or other material which will cause thereflectance of the cavity to be 0.5 % or less.6.2.2 Standard White Backing, having an effective absolutereflectance equal to 0.89 when illuminated under the conditionsof actual testing with a sheet of paper
23、in place (1).6Thisbacking consists either of a permanent diffusing surface of theapparent reflectance in contact with the sample, or of anequivalent cavity such as that provided by a diffusing surfaceseparated from the sample by a cover glass.6.2.3 Incandescent Light Source, with the color temperatu
24、readjusted to yield an overall instrumental response equivalent tothe Commission Internationale de lEclariage (CIE) functionEay which has an effective wavelength of 572 nm. In asingle-photocell instrument, stability requires that the voltagemust not change by more than approximately 0.1 %.6.2.4 Phot
25、ocell, in combination with optical filters and lampto produce an overall spectral response of the instrumentequivalent to Commission Internationale de lEclairage (CIE)function Eay (given in Table 1) which has an effectivewavelength of 572 nm and closely approximates the responseof the human eye.6.2.
26、5 Integrating Cavity, with inside surfaces coated withbarium sulfate or halon. Total area of non-white surfaces(including all openings) shall not exceed 6 % of the total whitearea. The specimen opening shall be round with a diameter of14.8 6 0.25 mm (0.584 6 0.010 in.). The illuminated areashall be
27、circular with a diameter of 9.53 6 0.38 mm (0.375 60.015 in.) and centered in the specimen opening. A light trapshould be fitted inside the integrating cavity to limit stray lightto no more than 0.5 %.7. Sampling and Test Specimens7.1 The material shall be sampled in accordance withPractice D 585.7.
28、2 When sampling for other than acceptance purposes,Practice E 122 may be used as an alternative.7.3 At least five representative specimens shall be selectedfor each test unit. They shall be free of watermarks orblemishes and of sufficient size to fit the specimen holder, andcompletely cover the stan
29、dard backings. The test areas shallnot be touched with the fingers, and these areas shall be keptperfectly clean and free of folds and wrinkles.8. Calibration8.1 Check the calibration utilizing evaluated opal glass orpaper standards and readjust as necessary in accordance withthe manufacturers instr
30、uctions and Annex A1. After calibra-tion, the instrument shall read the opal glass or paper standardswithin 60.3 of their assigned values.9. Conditioning9.1 Condition the test specimens in accordance with Prac-tice D 685.10. Procedure10.1 Opacity (89 % Reflectance Backing):6The boldface numbers in p
31、arentheses refer to the list of references at the end ofthis test method.TABLE 1 CIE EaY Weighting Functions, 10-nm Intervals(see Practice E 308)nmCIE EaY WeightingFunctionsnmCIE EaY WeightingFunctions400 0.000 600 7.547410 0.002 610 6.360420 0.008 620 5.061430 0.027 630 3.716440 0.061 640 2.559450
32、0.117 650 1.639460 0.209 660 0.971470 0.362 670 0.533480 0.618 680 0.289490 1.039 690 0.147500 1.802 700 0.075510 3.091 710 0.039520 4.756 720 0.020530 6.320 730 0.010540 7.599 740 0.005550 8.571 750 0.003560 9.219 760 0.001570 9.456 770 0.001580 9.224 780 0.000590 8.543D 589 97 (2002)210.1.1 Check
33、the calibration using an opal glass or paperstandard which is as close in value as possible to the specimento be measured. If agreement is not within 60.3 recalibrate asinstructed in Annex A.10.1.2 With the specimen backed by the standard whitebacking, set the instrument to read 100.0.10.1.3 Replace
34、 the white backing with the black body, andread the meter to obtain the contrast ratio. Record the indi-vidual results to three significant figures. Measure a minimumof five specimens.NOTE 2Usually neither the side nor direction of the grain of the papermakes any significant difference. If either ef
35、fect exceeds 0.2, place thespecimen with the selected side toward the instrument and in the selectedorientation, and state the conditions used in the report.10.2 Opacity (Paper Backing):10.2.1 Check the calibration using an opal glass or paperstandard which is as close in value as possible to the sp
36、ecimento be measured. If agreement is not within 60.3, recalibrate asinstructed in Annex A1.10.2.2 Place the specimen over the opening backed by a pileof the same paper. The thickness of the pile should be such thatdoubling the thickness has no detectable effect on the reading.Set the instrument to
37、read 100.0.10.2.3 Place the specimen over the opening backed by theblack body. The meter reading gives opacity with a paperbacking (100 R0/R). Record up to three significant figures.10.3 Scattering Power (sW)The ability to predict theeffect upon opacity due to a change of basis weight orreflectance
38、of a sheet has been found particularly useful topaper, pigment, and dyestuff manufacturers. The determinationof scattering power is the first essential step in making thesepredictions. Determine scattering power as follows:10.3.1 Obtain a white reflectance standard with knownabsolute reflectance at
39、572 nm.10.3.2 Carefully place the reference white surface over thespecimen opening of the instrument. Adjust the instrument toread the absolute reflectance value for the reference material (at572 nm).10.3.3 With the instrument adjusted to read correctly on theabsolute scale, place a single sheet of
40、the specimen over thespecimen opening backed by the black body and read R0.10.3.4 Leave the single specimen sheet (used in 10.3.3) inplace over the specimen opening and back with a pile of thesame paper. The thickness of the pile should be such thatdoubling the thickness has no detectable effect on
41、the reading.Read R.10.3.5 Using R0, R, and W (basis weight) in g/m2calculatescattering and absorption powers and coefficients as follows:a 5 0.5 1/R! 1 R# (1)b 5 0.5 1/R! 2 R!# (2)X 5 1 2 aR0# / bR0# (3)Scattering power sW = (0.5/ b) 1n (X + 1)/(X 1)Scattering coefficient: s 5 1000 sW/W (4)Absorptio
42、n power: kW 5 asW! 2 sW (5)Absorption coefficient: k 2 1000 kW/W (6)Scattering power and absorption power are unitless values.Scattering coefficient and absorption coefficient have inversebasis weight units: m2/kg.10.3.6 If the scattering power (sW) and reflectivity (R) areknown for a paper specimen
43、 of given basis weight, the opacityof the same specimen at a different basis weight (known asNormalized TAPPI Opacity, Cn) may be calculated as follows(2):Cn5a 2 1!0.89 2 R2 a0.89 2 1/R!#a/R! 2 R#0.89/R! 2 aR0.89 2 1/R!# 2 1#(7)where:sWn= normalized scattering power,BSWd= desired basis weight, andBS
44、Wk= known basis weight: sWn= sW (BSWd/BSWk)where Ris expressed as a decimal.a 5 esWn1/R! 2 R# (8)10.3.7 For further information concerning the calculationand use of scattering and absorption coefficients see TAPPITechnical Information Sheet 0804-03.11. Calculation11.1 Average the opacity values dete
45、rmined for each of thefive or more representative specimens tested from each testunit.11.2 Calculate the averages for opacity (89 % reflectancebacking) and opacity (paper backing) separately.12. Report12.1 Report the mean value and range for either or bothopacity values specified in this test method
46、, as agreed uponbetween the buyer and the seller.13. Precision and Bias13.1 The precision of this test method for test resultsconsisting of averages for five specimens is:13.1.1 Repeatability:13.1.1.1 89 % Backing0.62 %.13.1.1.2 Paper Backing 0.64 %.13.1.2 Reproducibility:13.1.2.1 89 % Backing1.22 %
47、13.1.2.2 Paper Backing 0.77 %.13.2 The above precision data are in conformance withTAPPI T 1206, and were obtained in the TAPPI CollaborativeReference Program for paper having opacities in the rangefrom 88 to 96 %. The data have been derived from Reports 12through 22 for 89 % backing (22 papers and
48、an average of 57laboratories) and Reports 19 through 22 for paper backing (8papers and an average of 13 laboratories).13.3 The user of these precision data is advised that it isbased on actual mill testing or laboratory testing, or both. Thereis no knowledge of the exact degree to which personnel sk
49、illsor equipment were optimized during its generation. TheD 589 97 (2002)3precision quoted provides an estimate of typical variation intest results which may be encountered when the test method isroutinely used by two or more parties.13.4 BiasThis test method has no bias, as the values foropacity are defined in terms of the specific procedures de-scribed.14. Keywords14.1 absorption coefficient; absorption power; contrast ra-tio; opacity (89 % reflectance backing); opacity meter; opacity(paper backing); paper; printing op
