ANSI T 515 OM-2014 Visual grading and color matching of paper.pdf

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1、TAPPI/ANSI T 515 om-14 SUGGESTED METHOD 1970 OFFICIAL STANDARD 1976 OFFICIAL TEST METHOD 1985 REVISED 1990 STANDARD PRACTICE 1999 REAFFIRMED 2009 REVISED 2014 2014 TAPPI The information and data contained in this document were prepared by a technical committee of the Association. The committee and t

2、he Association assume no liability or responsibility in connection with the use of such information or data, including but not limited to any liability under patent, copyright, or trade secret laws. The user is responsible for determining that this document is the most recent edition published. Appr

3、oved by the Standard Specific Interest Group for this Test Method TAPPI CAUTION: This Test Method may include safety precautions which are believed to be appropriate at the time of publication of the method. The intent of these is to alert the user of the method to safety issues related to such use.

4、 The user is responsible for determining that the safety precautions are complete and are appropriate to their use of the method, and for ensuring that suitable safety practices have not changed since publication of the method. This method may require the use, disposal, or both, of chemicals which m

5、ay present serious health hazards to humans. Procedures for the handling of such substances are set forth on Material Safety Data Sheets which must be developed by all manufacturers and importers of potentially hazardous chemicals and maintained by all distributors of potentially hazardous chemicals

6、. Prior to the use of this method, the user must determine whether any of the chemicals to be used or disposed of are potentially hazardous and, if so, must follow strictly the procedures specified by both the manufacturer, as well as local, state, and federal authorities for safe use and disposal o

7、f these chemicals. Visual grading and color matching of paper 1. Scope 1.1 This method describes the spectral, photometric, and geometric characteristics of a light source, the illuminating and viewing conditions, and the procedures to be used for the visual evaluation of color differences of paper,

8、 including those containing fluorescent whitening agents. 1.2 This method specifies light sources which are selected to accomplish three objectives: (a) simulation of the actual and illuminating conditions of ultimate use, (b) employment of two light sources which are spectrally very different in or

9、der to exaggerate observable differences between sample and standard if any difference exists, and (c) employment of a UV radiator to detect the presence of fluorescent whitening agents (FWA) and assess their impact on final appearance. 1.3 This method is applicable when the testers have normal colo

10、r vision. 2. Significance 2.1 In order to achieve the best possible agreement between customer and supplier on visual color matches, the same set of illuminating and viewing conditions must be employed by both customer and supplier. For example, if the customer will be using the paper in a typical o

11、ffice which is illuminated by cool white fluorescent (CWF) lighting, then the paper supplier should also use CWF as the light source for the visual assessment of the product. If the paper being evaluated contains optical brightening agents which fluoresce when excited by ultraviolet light, it is ver

12、y important that the customers light source be matched in the ultraviolet region as well as the visible region of the spectrum. Many observation booths are equipped with a UV light which may be added to any illuminant. Since its intensity is not calibrated, it does not match any standard illuminant

13、distribution but by adding UV light, the trained eye can assess the influence of the fluorescence and its impact on the final color. T 515 om-14 Visual grading and color matching of paper / 2 2.2 In many instances, colored paper products may be used and viewed in a wide variety of light sources. It

14、is recommended that such papers be visually color matched under two light sources which are spectrally quite different such as A and D65 or A and CWF. Doing so will exaggerate any color differences which may exist. This added discrimination capability allows one to better judge between closely match

15、ed specimens. 3. Apparatus 3.1 Light source. The light source is defined by the spectral distribution of the light energy incident on the specimen. This spectral power distribution results from a combination of the background, surround and the lamp or lamps employed. 3.1.1 Spectral power distributio

16、n. Table 1 contains the relative power distribution for the four standard illuminants which are most commonly used in the paper industry, viz, A, C, D65 and F2 (1, 2, 3). Standard Illuminant F2 is commonly known as cool white fluorescent (CWF) illumination. It is not possible to exactly duplicate th

17、e spectral power distribution of Standard Illuminant D65 in a physically realizable light source. Therefore, it must be understood that any physical D65 light source is an approximation of the actual D65 data shown in Table 1. Light used in observation booths is generally not standardized in the UV

18、region; therefore, assessment of FWA containing papers will provide only an approximation of proper fluorescence excitation. 3.1.2 Photometric conditions. For the general evaluation of papers of medium lightness, the illumination at the center of the viewed area is to be 807-1884 lumens/m2(75-175 fo

19、otcandles), but for critical evaluation of such papers it is to be 1076-1345 lumens/m2(100-125 footcandles). NOTE 1: For the evaluation of very light papers, the illumination may be reduced to as low as 538 lumens/m2(50 footcandles), and for very dark papers it may be increased to as high as 2153 lu

20、mens/m2(200 footcandles). 3.1.3 Geometric conditions. The specimen is to be illuminated from an overhead extended-area source. The illumination over the viewing area should be diffuse and uniform to within 20%, and abrupt changes in illumination level are not to be visible. 3.1.4 Background and surr

21、ound. 3.1.4.1 The viewing area is to be shielded from extraneous light, preferably by a permanent structure. The background should be matte gray with a maximum reflectance of 65.0% and a minimum reflectance of 50.0% measured at an effective wavelength of 557nm. 3.2 Illumination meter1, suitable for

22、measuring the illumination of the viewing area with a minimum scale of 538-2153 lumens/m2(50-200 footcandles). 3.3 Both the specimen and reference papers should be in the form of an opaque pad. The pad should generally be at least 150 250 mm (6 10 in.) in size and thick enough to be opaque. 4. Sampl

23、ing and test specimens Obtain the sample in accordance with TAPPI T 400 “Sampling and Accepting a Single Lot of Paper, Paperboard, Containerboard, or Related Product.” Select specimens at least 150 250 mm (6 10 in.) in size, uniform in color and gloss, free from imperfections in surface texture, and

24、 free from fingerprints and other blemishes. Curl, cockle or large differences in smoothness may affect the evaluation. 5. Procedure 5.1 Cover half of the top area of the reference pad with a specimen and place both at the distance from the light source needed to obtain the required illumination. Us

25、e the illumination meter to determine the proper distance. Avoid any perceptible specular (gloss) reflection of the light source by the specimen. If the source is directly overhead (preferred), place the specimen and pad horizontally and view them at an approximate angle of 45 from the perpendicular

26、. Interchange the positions of the specimen and the reference pad and reevaluate the difference. It is usually desirable to match the specimens under multiple sources as indicated in section 1.2, 2.1 and 2.2. 1Names of suppliers of testing equipment and materials for this method may be found on the

27、Test Equipment Suppliers list, available as part of the CD or printed set of Standards, or on the TAPPI website general Standards page. 3 / Visual grading and color matching of paper T 515 om-14 Table 1. Relative Spectral Power Distributions of CIE Standard Illuminants A, C, D65 and F2. (nm) A C D65

28、 F2 300 0.93 0.03 305 1.13 1.70 310 1.36 3.30 315 1.62 11.80 320 1.93 0.01 20.20 325 2.27 0.20 28.60 330 2.66 0.40 37.10 335 3.10 1.55 38.50 340 3.59 2.70 39.90 345 4.14 4.85 42.40 350 4.74 7.00 44.90 355 5.41 9.55 45.80 360 6.14 12.90 46.60 365 6.95 17.20 49.40 370 7.82 21.40 52.10 375 8.77 27.50 5

29、1.00 380 9.80 33.00 49.98 1.18 385 10.90 39.92 52.31 1.48 390 12.09 47.40 54.65 1.84 395 13.35 55.17 68.70 2.15 400 14.71 63.30 82.75 3.44 405 16.15 71.81 87.12 15.69 410 17.68 80.60 91.49 3.85 415 19.29 89.53 92.46 3.74 420 20.99 98.10 93.43 4.19 425 22.79 105.80 90.06 4.62 430 24.67 112.40 86.68 5

30、.06 435 26.64 117.75 95.77 34.98 440 28.70 121.50 104.86 11.81 445 30.85 123.45 110.94 6.27 450 33.09 124.00 117.01 6.63 455 35.41 123.60 117.41 6.93 460 37.81 123.10 117.81 7.19 465 40.30 123.30 116.34 7.40 470 42.87 123.80 114.86 7.54 475 45.52 124.09 115.39 7.62 480 48.24 123.90 115.92 7.65 485 5

31、1.04 122.92 112.37 7.62 490 53.91 120.70 108.81 7.62 495 56.85 116.90 109.08 7.45 500 59.86 112.10 109.35 7.28 505 62.93 106.98 108.58 7.15 510 66.06 102.30 107.80 7.05 515 69.25 98.81 106.30 7.04 520 72.50 96.90 104.79 7.16 525 75.79 96.78 106.24 7.47 530 79.13 98.00 107.69 8.04 535 82.52 99.94 106

32、.05 8.88 540 85.95 102.10 104.41 10.01 545 89.41 103.95 104.23 24.88 550 92.91 105.20 104.05 16.64 555 96.44 105.67 102.02 14.59 560 100.00 105.30 100.00 16.16 565 103.58 104.11 98.17 17.56 570 107.18 102.30 96.33 18.62 575 110.80 100.15 96.06 21.47 580 114.44 97.80 95.79 22.79 585 118.08 95.43 92.2

33、4 19.29 590 121.73 93.20 88.69 18.66 595 125.39 91.22 89.35 17.73 Table continued next page T 515 om-14 Visual grading and color matching of paper / 4 (nm) A C D65 F2 600 129.04 89.70 90.01 16.54 605 132.70 88.83 89.80 15.21 610 136.35 88.40 89.60 13.80 615 139.99 88.19 88.65 12.36 620 143.62 88.10

34、87.70 10.95 625 147.24 88.06 85.49 9.65 630 150.84 88.00 83.29 8.40 635 154.42 87.86 83.49 7.32 640 157.98 87.80 83.70 6.31 645 161.52 87.99 81.86 5.43 650 165.03 88.20 80.03 4.68 655 168.51 88.20 80.12 4.02 660 171.96 87.90 80.21 3.45 665 175.38 87.22 81.28 2.96 670 178.77 86.30 82.28 2.55 675 182.

35、12 85.30 80.28 2.19 680 185.43 84.00 78.28 1.89 685 188.70 82.21 74.00 1.64 690 191.93 80.20 69.72 1.53 695 195.12 78.24 70.67 1.27 700 198.26 76.30 71.61 1.10 705 201.36 74.36 72.98 0.99 710 204.41 72.40 74.35 0.88 715 207.41 70.40 67.98 0.76 720 210.36 68.30 61.60 0.68 725 213.27 66.30 65.74 0.61

36、730 216.12 64.40 69.89 0.56 735 218.92 62.80 72.49 0.54 740 221.67 61.50 75.09 0.51 745 224.36 60.20 69.34 0.47 750 227.00 59.20 63.59 0.47 755 229.59 58.50 55.01 0.43 760 232.12 58.10 46.42 0.46 765 234.59 58.00 56.61 0.47 770 237.01 58.20 66.81 0.40 775 239.37 58.50 65.09 0.33 780 241.68 59.10 63.

37、38 0.27 5.2 Observe the degree of color difference between each specimen and the reference pad in terms of hue, lightness, saturation, and overall match as follows: 5.2.1 Hue, the attribute of color perception by means of which an object is judged to be red, yellow, green, blue, purple, or intermedi

38、ate between some adjacent pair of these. 5.2.2 Lightness, an attribute of color perception by which an object is graded on its reflected intensity from black to white. 5.2.3 Saturation, an attribute of color perception used to indicate the degree of departure of a color from a gray of the same light

39、ness. 5.2.4 Overall match, expressed as “excellent,” if much better than tolerance; “good,” if definitely better than tolerance; “fair,” if about as close as tolerance, and “poor,” if worse than tolerance. For example, the difference between two red colors might be given as “moderately yellower (hue

40、), slightly darker (lightness), very slightly less saturated, overall match, fair.” 5.2.5 Before assessment, observe samples under light from a UV radiator only. A blue fluorescence from the samples indicates clearly the presence of FWA. This is readily seen with white samples. Many yellow samples a

41、lso show fluorescence to some degree. 5.2.6 If fluorescence has been detected, color attributes must be assessed also in the presence and the absence of UV radiation. Since the amount of UV coming from the radiator is not standardized, the impact of fluorescence on final appearance can only be estim

42、ated. A good practice is to observe samples under two pieces of flat, transparent plastic; one totally transparent in the UV and the other containing a UV absorber. First look for metamerism of the samples under normal illumination without UV radiation. Assess fluorescence as: 5 / Visual grading and

43、 color matching of paper T 515 om-14 Intensity - compare and estimate the amount of fluorescence on both samples. Shade - characterize the shade of the outgoing fluorescence as redder, equal or greener than standard. Assess the final perceived whiteness of the samples in terms of: Whiteness - the at

44、tribute of color perception by means of which an object appears more or less white than standard. Shade - the attribute of color perception by means of which the perceived white object appears redder, equal or greener than standard. Blueness - the attribute of color perception by means of which an o

45、bject appears whiter because of higher blue saturation but less light intensity. Overall match, expressed similar to 5.2.4. For example, the difference between two white samples might be given as “slightly less white (whiteness), moderately redder (shade), slightly bluer or duller (blueness).” 6. Re

46、port 6.1 Include the following information as required: 6.1.1 Type of evaluation, approximate, general, or critical. 6.1.2 Description of the reference paper and the specimen, including their gloss and surface characteristics. 6.1.3 Intensity of illumination, direction of illumination and viewing, a

47、nd source identification. 6.1.4 Degree of color difference observed. 6.1.5 Any departures from the recommendations in this method. 6.1.6 Identity of the observer or a note as to the observers ability and experience. 7. Precision This method returns a subjective result that describes in text the diff

48、erences that can occur between color samples. These differences are difficult to quantify and can vary significantly depending on the experience of the user and the color match tolerance required for a given situation. The determination of repeatability and reproducibility is therefore not possible

49、for this method. 8. Keywords Vision, Color, Light sources, Paper, Fluorescent dyes, Illumination, Color matching, Colorimetry, Visual grading 9. Additional information 9.1 Effective date of issue: April 30, 2014 9.2 Related methods: ASTM D1729 “Visual Evaluation of Color Differences of Opaque Materials,” American Society for Testing and Materials, Philadelphia, PA; BS 950, Part 1, British Standards Institution, London, England; “Colorimetry,” Official Recommendations of the International Commission on Illumination, Publication CIE No. 15 (1971), and “Method of Me