1、BRITISH STANDARD BS 2782-5: Method 520A: 1992 Methods of testing Plastics Part 5: Optical and colour properties, weathering Method 520A: Determination of specular gloss IMPORTANT NOTE. Before reading this method it is essential to read BS2782-0, Introduction, issued separately.BS2782-5:Method520A:19
2、92 This British Standard, having been prepared under the directionof the Plastics and RubberStandards Policy Committee, was published underthe authority of the Standards Board and comes intoeffect on 28 February1992 BSI 06-1999 The following BSI references relate to the work on this standard: Commit
3、tee reference PRM/21 Draft for comment 91/37748 DC ISBN 0 580 20463 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Plastics and Rubber Standards Policy Committee (PRM/-) to Technical Committee PRM/21, upon which the following bodies w
4、ere represented: British Plastics Federation British Steel Industry British Telecommunications plc British Textile Confederation Department of Trade and Industry (National Physical Laboratory) EEA (the Association of Electronics, Telecommunications and Business Equipment Industries) Electrical and E
5、lectronic Insulation Association (BEAMA Ltd.) Electrical Installation Equipment Manufacturers Association (BEAMA Ltd.) GAMBICA (BEAMA Ltd.) Ministry of Defence Packaging and Industrial Films Association PIRA Plastic Industrial Containers Association RAPRA Technology Ltd. Yarsley Technical Centre Ltd
6、. Amendments issued since publication Amd. No. Date CommentsBS2782-5:Method520A:1992 BSI 06-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Principle 1 4 Apparatus 1 5 Reference standards 2 6 Test specimens 2 7 Procedure 2 8 Test report 4 Append
7、ix A Precision 5 Figure 1 Schematic diagram of a glossmeter 3 Table 1 Angles and relative dimensions of source image and receptor apertures 3 Table 2 Maximum acceptable differences for two results 5BS2782-5:Method520A:1992 ii BSI 06-1999 Foreword This British Standard has been prepared under the dir
8、ection of the Plastics and Rubber Standards Policy Committee. It supersedes Method515B of BS2782:1970 which is withdrawn by amendment. WARNING NOTE. This British Standard does not necessarily detail all precautions necessary to meet the requirements of the Health and Safety at Work etc. Act1974. Att
9、ention should be paid to any appropriate safety precautions and the method should be operated only by trained personnel. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance wit
10、h a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to5 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This
11、 will be indicated in the amendment table on theinside front cover.BS2782-5:Method520A:1992 BSI 06-1999 1 1 Scope This British Standard describes a method of test for measuring, relative to a standard surface, the specular gloss of plastics specimens for glossmeter geometries of60,20 and85. NOTEAppe
12、ndix A indicates the precision likely to be obtained from the test. 2 Definitions For the purposes of this British Standard the following definitions apply. 2.1 specular gloss the relative luminous reflectance factor of a specimen in the mirror direction 2.2 gloss the reflective response of a surfac
13、e, which is the radiation reflected in the geometric direction at the surface including radiation scattered forward at very low angles to the geometric direction 2.3 relative luminous reflectance factor the ratio of the luminous flux reflected from a specimen to the luminous flux reflected from a st
14、andard surface under the same geometric conditions, when angles of incidence and reflection are measured with respect to the normal to the surface NOTEFor the purpose of measuring specular gloss the standard surface is polished black glass. 3 Principle Gloss is associated with the capacity of a surf
15、ace to reflect more light in some directions than in others. The directions associated with mirror (or specular) reflection normally have the highest reflectances. Specular reflectance depends on the surface refractive index of the specimen. Therefore, it is customary to compare the specular reflect
16、ances of two specimens having similar refractive indices. Instrumental ratings are affected more than visual ratings by changes in surface refractive index and when high gloss surfaces differing in refractive index are compared it is likely that visual and instrumental gloss ratings will differ. In
17、this method highly polished, plane, black glass, with a refractive index of1.567 for the sodium D line, is assigned a gloss value of100 for each geometry. Measured gloss ratings for the materials under test are obtained by comparing the specular reflectance from the specimen to that from the standar
18、d black glass under identical conditions of test. For general use the60 geometry is used. When gloss readings at60 are higher than70, the20 geometry is recommended. When gloss readings at60 are lower than10, the85 geometry is recommended. 4 Apparatus 4.1 Glossmeter, consisting of a light source and
19、a lens that directs a parallel beam of light on to the surface under test and a receptor housing containing a lens, field stop and photoelectric cell to receive the required cone of reflected light and having the following characteristics. The axis of the incident beam shall be at20 0.1,60 0.1 or85
20、0.1 (see Table 1) to the perpendicular to the surface under test. The axis of the receptor shall coincide with the mirror image of the axis of the incident beam within a tolerance of 0.1. With a flat piece of polished black glass or a front-surface mirror in the test panel position, an image of the
21、source shall be formed at the centre of the receptor field stop (receptor window). For averaging over the surface, the width of the illuminated area of the test panel shall be significantly larger than possible surface structures: a generally accepted value is10mm. The angles and relative dimensions
22、 of the source image and receptor apertures shall be as indicated in Table 1. NOTE 1As specular gloss is, for practical purposes, spectrally non-selective, the spectral characteristics of the light source and the detector need to be critically controlled only when measuring highly chromatic, low glo
23、ss plastics or when specular reflectance produces an obvious chromatic shift in the colour the incident light. In this case, the combination of light, source, photoelectric cell and associated colour filters will give a spectral sensitivity approximating to the CIE 1)photopic luminous efficiency fun
24、ction, weighted for CIE standard illuminants C or D65. NOTE 2The tolerances have been chosen so that errors in the source and receptor apertures will not produce reading errors of more than one gloss unit at any point on a100unit scale (see5.1). NOTE 3Figure 1 shows a schematic diagram of the essent
25、ial features of the glossmeter. 1) International Commission on Illumination, Central Bureau, Kegelgasse, 27, A-1033 Vienna, Austria.BS2782-5:Method 520A:1992 2 BSI 06-1999 NOTE 4An evaluation of the impact of polarization on gloss measurement has been reported. The magnitude of the polarization erro
26、r depends on the difference between the refractive indices of specimen and standard, the angle of incidence, and the degree of polarization. As the specimen and standard are generally quite similar optically, measured gloss values are little affected by polarization. There shall be no vignetting of
27、rays that lie within the field angles specified in Table 1. The receptor-measurement mechanism shall give a numerical indication that is proportional to the light flux passing the receptor field stop with1% of full-scale reading. If transparent plastics are to be measured, the measurement mechanism
28、shall be capable of measuring up to200 units. 5 Reference standards 5.1 Primary standards Highly polished, plane, black glass with a refractive index of1.567 for the sodium D line shall be assigned a specular gloss value of100 for each geometry. NOTE 1For small differences in refractive index, the g
29、loss value is a linear function of index, but the rate of change of gloss with index is different for each geometry. Each0.001 increment in refractive index produces a change of0.27,0.16 and0.016 in the gloss value assigned to a polished standard for the20,60 and85 geometries, respectively. For exam
30、ple, glass of index1.527 would be assigned values of89.2,93.6 and99.4, in order of increasing geometry. NOTE 2Polished black glass has been reported to change in refractive index with time largely due to chemical contamination. The original values can be restored by optical polishing with cerium oxi
31、de. A wedge of high-purity quartz provides a more stable reference standard than glass. 5.2 Working standards NOTECeramic tile, de-polished ground opaque glass, emery paper, and other semi-gloss materials having hard and uniform surfaces are suitable. Working standards shall be calibrated against a
32、primary standard(5.1) and the calibration checked periodically for constancy by comparing with primary standards. 5.3 Maintenance of primary and working standards 5.3.1 Storage Standards shall be stored in a closed container when not in use. They shall be kept clean and away from any dirt that might
33、 scratch or mar their surfaces. 5.3.2 Handling Always hold the standards at the side edges to avoid getting oil from the skin on the standard surface. Do not place the standards face down on a surface that may be dirty or abrasive. 5.3.3 Cleaning Clean the standards in a mild detergent solution in w
34、arm water, brushing gently with a soft nylon brush. NOTEDo not use soap solutions because they may leave a film. Rinse the standards after cleaning in running water at65 5 C to remove detergent solution. Rinse again in distilled water at ambient temperature. Do not wipe the standards. The primary st
35、andards (5.1) may be dabbed gently with a lint-free paper towel or other lint-free absorbent material. 5.3.4 Drying Dry the standards in a drying oven at110 5 C for at least four hours. 6 Test specimens The test specimen shall be flat and at least150mm 75mm with the exception that if manufacturing m
36、ethods make the production of a specimen of this size impractical, smaller specimens can be used. The size of any such smaller specimens shall be given in the test report. The test specimens shall be protected against contamination and damage before testing. 7 Procedure 7.1 Instrument calibration 7.
37、1.1 Verify the instrument zero by placing a black cavity in the specified position. If the reading is not within 0.1 of zero, subtract it algebraically from subsequent readings or adjust the instrument to read zero. 7.1.2 Calibrate the instrument at the start and completion of every period of glossm
38、eter operation, and during the operation at sufficiently frequent intervals to assure that the instrument response is practically constant. To calibrate, adjust the instrument to read correctly the gloss of a primary standard(5.1) properly positioned and oriented, and then read the gloss of working
39、standard(5.2) in the mid-gloss range. If the instrument reading for the working standard does not agree within one unit of its assigned values, check its cleanliness and repeat. If the instrument reading for the working standard still does not agree within one unit of its assigned value, repeat with
40、 another mid-gloss range working standard. If the disparity is still more than one unit, do not use the instrument without readjustment, preferably by the manufacturer. 7.2 Measurement 7.2.1 Position each specimen in turn beneath (or on) the glossmeter. For specimens with surface texture effects, pl
41、ace them so that the direction of the texture effects are parallel to the plane of the axes of the incident and reflected beams. Place transparent plastics on a black surface, such as velvet.BS2782-5:Method520A:1992 BSI 06-1999 3 Table 1 Angles and relative dimensions of source image and receptor ap
42、ertures Aperture In plane of measurement Perpendicular to plane of measurement 2 tan /2 Relative dimension 2 tan /2 Relative dimension in degrees in degrees Source image 0.75 0.0131 0.171 2.5 0.0436 0.568 Tolerance 0.25 0.0044 0.057 0.5 0.0087 0.114 60 receptor 4.4 0.0768 1.000 11.7 0.2049 2.668 Tol
43、erance 0.1 0.0018 0.023 0.2 0.0035 0.046 20 receptor 1.8 0.0314 0.409 3.6 0.0629 0.819 Tolerance 0.05 0.0009 0.012 0.1 0.0018 0.023 85 receptor 4.0 0.0698 0.909 6.0 0.1048 1.365 Tolerance 0.3 0.0052 0.068 0.3 0.0052 0.068 Figure 1 Schematic diagram of a glossmeterBS2782-5:Method 520A:1992 4 BSI 06-1
44、999 7.2.2 Take three readings on a150mm 75mm area of the test specimen, or the whole area for smaller specimens (see clause6). If the range of readings is greater than two gloss units take four more readings and calculate the mean of the seven readings obtained. 7.2.3 On larger test specimens take t
45、hree readings on representative areas measuring150mm 75mm, increasing the number of readings as in7.2.2 if the range of readings is greater than two gloss units. Calculate the mean. 8 Test report The test report shall include the following information: a) a complete identification of the material te
46、sted, including manufacturers code, grade and form; b) a reference to this British Standard, i.e.BS2782:Method520A; c) a description or identification of the method of preparation, otherwise the statement that the material has been tested as received; d) the type of glossmeter used, including the ma
47、nufacturers name and model number; e) the working standards and standards of gloss used; f) the size of test specimen, if below the minimum size specified (see clause6); g) the angles of incidence and reflection; h) the mean specular gloss readings; i) the individual test results; j) the name of the
48、 test house; k) the date on which the tests were conducted.BS2782-5:Method520A:1992 BSI 06-1999 5 Appendix A Precision A.1 Repeatability Two results, each of which are single determinations obtained on the same specimen by the same operator, should not differ by more than the amounts given in Table
49、2. Table 2 Maximum acceptable differences for two results A.2 Reproducibility Two results, each of the mean of three determinations, obtained on the same specimen by different laboratories should not differ by more than the amounts given in Table 2. This does not include variability due to preparation of panels in different laboratories. Angle of measure ment Repeatability (within laboratories) Reproducibility (between laboratories) Ceramic tiles Painted panels Ceramic tiles Painted panels 20 1.1 1.7 3.5 6.4 60 0.
