ANSI T 1212 SP-2007 Light sources for evaluating papers including those containing fluorescent whitening agents.pdf

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1、T 1212 sp-12 FORMERLY TIP 0804-01 STANDARD PRACTICE 1998 REVISED 2002 REVISED 2007 REAFFRIMED 2012 2012 TAPPI The information and data contained in this document were prepared by a technical committee of the Association. The committee and the Association assume no liability or responsibility in conn

2、ection 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. Approved by the Standard Specific Interest Group for this Test M

3、ethod 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. The user is responsible for determining that the safety pre

4、cautions 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 may present serious health hazards to humans. Procedures for

5、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. Prior to the use of this method, the user must determine w

6、hether 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 of these chemicals. Light sources for evaluating papers inclu

7、ding those containing fluorescent whitening agents 1. Scope 1.1 This standard practice covers the significance and application of both instrumental and visual light sources for evaluating papers and related materials including those containing fluorescent whitening agents. The information presented

8、is based on accepted or current proposals of the Inter Society Color Council (ISCC), Commission Internationale dEclairage (CIE), International Standards Organization (ISO), American National Standards Institute (ANSI), TAPPI, and TAPPI Optical Properties Committee experience. Also presented is a met

9、hod for the visual evaluation of a color match under standard conditions of illumination. 2. Significance 2.1 Light sources are commonly described by their color temperature. 2.2 Common tungsten filament lamp color temperature is a very close approximation to the black body color temperature. These

10、sources have a smooth and continuous spectral energy distribution. Non-black bodylight sources are described by their correlated color temperature which is the color temperature of a black body which they most closely resemble. Such sources are, for example, arc lamps whose spectral energy distribut

11、ions are not continuous, but rather have concentrated energy in a few very narrow wavelength regions, or fluorescent lamps which do have continuous spectrums but superimposed with a few narrow wavelength regions of concentrated energy. In all cases, the spectral energy distribution for a light sourc

12、e at a given color temperature is defined in the visible portion only and does not include the amount or distribution of energy in the ultraviolet (UV) which excites fluorescent whitening or brightening agents. For these reasons, the description of a light source or an illuminant by giving the color

13、 temperature or correlated color temperature alone is not entirely satisfactory. 2.3 When viewing papers or related materials containing fluorescent whitening or brightening agents, the illumination must have a suitable form, must be continuous (not have significant energy located in a few spectral

14、lines only), and must contain a sufficient amount of UV radiation to excite the fluorescent agent. The visual appearance of paper containing such an agent will depend on the relative amount of UV energy present in the illumination. 2.4 If only the presence of a fluorescent whitening agent in a mater

15、ial needs to be determined, then a light source rich in ultraviolet energy with only a very small amount of visible light should be used. A mercury lamp such as Ultraviolet Products Black-Ray UVL-21 which operates on 115 V ac is suitable for this purpose. When a sample is T 1212 sp-12 Light sources

16、for evaluating papers including / 2 those containing fluorescent whitening agents viewed in the dark under such illumination, spot fluorescent contaminants can be distinguished from a uniform overall application of a fluorescent material. 3. Definitions 3.1 Definitions of technical terminology used

17、in this standard practice may be found in TAPPI T 1213 “Optical Measurements Terminology (related to appearance evaluation of paper).” 4. Index of light sources 4.1 Table 1 is an index of light sources referred to in this document. 4.2 Specific light sources and illuminants The applicable light sour

18、ces are described by their approximate correlated color temperatures as follows: 4.2.1 2300-2854 K 4.2.1.1 The color of off-white papers may vary with the quality of the illuminant. To evaluate this effect, the specimen is viewed alternately under sources of low and high temperatures. Two low temper

19、ature illuminants have been in common use. One has a color temperature of 2300 K and is known as horizon light; the other is CIE Illuminant A which has a color temperature of 2854 K. Table 1. Index of light sources. Correlated color temperature, K Name of lamp Manufacturer Section (UV only) - Ultra-

20、violet Products 4.2.1 2300-2854 Tungsten filament G. E. Sylvania, etc. 4.2.1 3000 ANSI Code CPR G. E. PH/18AT 10P-6V 4.2.2 3000 No. 38 02 07 Carl Zeiss, Inc. 4.2.2 2800-3400 Tungsten-halogen G. E. and Sylvania 4.2.2 3800 Avlite GretagMacbeth 4.2.3 3800 Colorarc Sylvania 4.2.3 4000-4200 Deluxe cool w

21、hite fluorescent Sylvania 4.2.4 5000 Macbeth 5000 fluorescent lamps in Prooflite D5000System GretagMacbeth 4.2.6 5000 Metalarc Sylvania 4.2.6 5900 |XBO Xenon Arc Osram 4.2.6 6000 Xenon Lamp in Elrepho Photometer Zeiss 4.2.6 6500 Norlite D6500Illumination systems GretagMacbeth 4.2.7 6500 Osram Xenon

22、XBF + filter Osram 4.2.7 6500 Xenon lamp + filter in DMC 25 Spectrophotometer Zeiss 4.2.7 6770 Illuminant C - 4.2.8 North Sky 7400 Macbeth Skylight Illumination System GretagMacbeth 4.2.9 North Sky 7500 Macbeth Skylight Illumination System GretagMacbeth 4.2.9 7500 Macbeth 7500 Fluorescent Lamps in N

23、orlite D7500System GretagMacbeth 4.2.9 4.2.1.2 Two committees have adopted incandescent light at 2300 K (in conjunction with standard fluorescent light of 4400 K) as a standard for the detection of metamerism by visual viewing. ISCC Subcommittee for Problem 21 is proposing 2300 100 K with a Color Re

24、ndering Index (CIE R) = 92-100 in the Standard Practices for Visual Examination of Small Color Differences. ASTM Committee D-1 for the revision of D-1729-64 has also selected 2300 K with CIE Ra= 92-100 for Visual evaluation of Color Differences of Opaque Materials. 4.2.1.3 ASTM D-1729-60t specified

25、a light source of 2854 K with tolerances of 100 K for an AA match or 75 K for an AAA match. In this method, the 2854 K source is augmented with a higher color temperature source, 7500 K and 7400 K respectively, for determining if a metameric match has been made. 4.2.1.4 The CIE official recommendati

26、ons on colorimetry states that CIE Illuminant A represents the Planckian radiator (black body) at 2854 K and gives relative spectral power distribution from 380 to 780 nm. It is a standard source for instrumental determinations as well as visual viewing. Sources for 2300 K and 2854 K are calibrated

27、gas-filled 3 / Light sources for evaluating papers including T 1212 sp-12 those containing fluorescent whitening agents tungsten filament lamps operated at the proper conditions to give the specified color temperature. 4.2.2 3000 K 4.2.2.1 An incandescent source is used for most instrumental colorim

28、etric work. The highest available color temperature is used in order to obtain the maximum available ultraviolet energy. 4.2.2.2 The relative spectral energy distributions of several nominal 3000 K sources used in instrumental work for the light incident on the specimen are shown in Fig. 1. The curv

29、es have been normalized to be equal to 100 at 500 nm. Many Technidyne brightness and color testers use a quartz tungsten halogen (QTH) lamp, but with a heat absorbing filter. Many Hunter Color-Difference Meters likewise use a QTH lamp, a 6.9 mm (0.27 in.) thick Pittsburgh Plate Glass 2043 heat absor

30、bing filter, and silicate-coated aluminum mirror which further reduces the relative amount of radiation above 600 nm. All of these sources provide essentially the same spectral energy distribution incident upon the specimen from 320 to 500 nm, but beyond this it varies as shown in Fig. 1. Fig. 1. Re

31、lative spectral energy distributions. 4.2.2.3 Quartz tungsten halogen (QTH) lamps contain a tungsten filament and halogen in a fused quartz envelope. In the higher wattages, they can be operated at color temperatures as high as 3400 K and consequently emit slightly more ultraviolet radiation than st

32、andard glass envelope incandescent lamps, particularly since the quartz envelope will pass radiation down to 250 nm. The principal advantage of tungsten-halogen lamps is that the halogen combines with evaporated tungsten (vapor) and prevents it from being deposited on the inside of the lamp envelope

33、, thereby eliminating blackening. This keeps the lamp clean, greatly increases its efficiency, and reduces changes in the intensity and spectral distribution of the radiation due to bulb blackening, thus permitting the use of the lamp until it burns out. 4.2.3 3800 K 4.2.3.1 This color temperature i

34、s used for visual viewing only. ANSI PH 2.23-1961, “American Standard Lighting Conditions for Viewing Photographic Color Prints and Transparencies,” presently specifies 3800 K. 4.2.3.2 Two light sources which approach the 3800 K source are the Macbeth Avlite and Sylvania Colorarc. The Avlite is a bi

35、pin fluorescent lamp available in several wattages. The Colorac is a mogul screw base iodide arc lamp available in several wattages. 4.2.4 4000 to 4200 K The fluorescent lamps used in many color laboratories, office areas, and commercial establishments selected as a close quality match to natural da

36、ylight are the deluxe cool white lamps. The color rendering index for most manufacturers lamps for a correlated color temperature of 4000 to 4200 K is approximately 86. 4.2.5 4400 K The ISCC selected a color temperature of 4400 K for their standard fluorescent illumination in conjunction with 2854 K

37、 for detection of metamerism. See material included under light source 2300-2854 K for specific references to methods. T 1212 sp-12 Light sources for evaluating papers including / 4 those containing fluorescent whitening agents 4.2.6 5000 K 4.2.6.1 In the graphic arts industries, standard illuminant

38、 D50 provides an average condition representing various aspects of actual use. When color matches are made at a low color temperature such as 3800 K or at a high color temperature such as 7500 K, the results are sometimes very poor when viewed under the opposite extreme. Skin tones, for example, whi

39、ch are most critical to the eye, may be a very poor match and not pleasing. D50 is an average of these extremes and has the most neutral spectral response of all standard daylight illuminants. The average office fluorescent light mixed with north sky daylight also falls near 5000 K. It probably is t

40、he best color temperature to represent average color viewing conditions but is known to overexcite optical brightening agents (OBAs) when present. 4.2.6.2 Several standards have been proposed or are approved for use of CIE illuminant D50 which specifies the spectral power distribution from 300 to 83

41、0 nm. These include: ANSI Standard Viewing Conditions for the PH2.32 Appraisal of Color Quality and Color Uniformity in the Graphic Arts Industry BSI Standard 950 Illumination and Viewing Part 2 Conditions for Reproduction in (Great Britain) the Graphic Arts (as revised in 1968) ISO TC 42/WG7 Illumi

42、nation for Comparison International Viewing of Photographic Transparencies and Reflection Color Prints AFNOR (France) Conditions for comparison reflection reproductions with photographic transparencies or original art work JOERA Standard Standard Conditions for Lighting and Viewing Color Transparenc

43、ies and Prints 4.2.6.3 Macbeth Corporation manufactures GretagMacbeth Prooflite D50 Illumination Systems using 15- and 4-W GretagMacbeth 5000 Fluorescent Lamps. The correlated color temperature of these illumination systems is 5000 K and is claimed to meet the ANSI Standard referred to above. 4.2.6.

44、4 Osram manufactures a unique XBO Xenon high pressure lamp. It has a relatively continuous spectrum in the visible range with little ultraviolet below 300 nm but has strong peaks in the infrared at 820, 900, and 980 nm. The correlated color temperature of these lamps is approximately 5900 K. The lam

45、p envelope is quartz and the discharge is the short arc type. Osram lamps are distributed in the United States by Macbeth Sales Corporation. 4.2.6.5 Sylvania manufactures a Metalarc lamp which is a high pressure mercury arc lamp but with the addition of a metal iodide to the mercury vapor. It has a

46、correlated color temperature near 5000 K. The spectral distribution changes with ambient temperature. 4.2.7 6500 K 4.2.7.1 A color temperature of 5000 K is suited for appraising the color of most objects as viewed under average conditions. It does not, however, accentuate the difference between the

47、yellowish tint of two near-white colors as well as one of 7500 K. A compromise between the two is 6500 K. When viewing optically brightened papers illuminant D65 may be used if the object of the evaluation is to accentuate the effect of fluorescent whitening agents, for color difference determinatio

48、n. The use of D65 is discouraged, however, when the object is to make comparisons in illumination similar to end use conditions, as D65 is known to overexcite optical brightening agents (OBAs) relative to visual assessment under end use conditions. Standard illuminant C more closely duplicates the s

49、pectral distribution of average office 5 / Light sources for evaluating papers including T 1212 sp-12 those containing fluorescent whitening agents lighting particularly in the ultra-violet portion of the spectrum. Table 2. Spectral power distribution of CIE Illuminant D65. Relative power Relative power Wavelength, per unit Wavelength, per unit nm wavelength nm wavelength 300 0.03 570 96.3 310 3.3 580 95.8 320 20.2 590 88.7 330 37.1 600 90.0 340 39.9 610 89.6 350 44.9 620 87.7 360 46.6 630 83.3 370 52.1 640 83.7 380 50.0 650 80.0 390 54.6 660 80.2 400 82.8 670 82.3