AS NZS 1301.545:2018 pdf download.Methods of test for pulp and paper Method 545: Determination of light scattering and absorption coefficients (using Kubelka-Munk theory) (ISO 9416:2017, MOD)
4 Principle
The luminance factor of a single sheet of the paper over a black cavity and the intrinsic luminance factor of the paper are determined. The grammage is determined in accordance with Iso 536.
The light-absorption and light-scattering coefficients are then calculated from these data using the Kubelka-Munk theory.
5 Apparatus
5.1 Reflectometer, having the geometric, spectral and photometric characteristics described in ISO 2469, equipped for the measurement of luminance factor, and calibrated in accordance with the provisions of ISO 2469.
5.2 Filter-function. In the case of a filter reflectometer, a filter that, in conjunction with the optical characteristics of the basic instrument, gives an overall response equivalent to the CIE tristimulus value Y of the CIE 1931 standard colorimetric system of the test piece evaluated for the CIE illuminant C.
In the case of an abridged spectrophotometer, a function that permits calculation of the CIE tristimulus value Yof the CIE 1931 standard colorimetric system of the test piece evaluated for the CIE illuminant C using the weighting functions given in Annex A.
5.3 UV-cut-off filter. To eliminate any fluorescence effect, the instrument shall be equipped with a sharp cut-off, UV-absorbing filter having a transmittance not exceeding 0,5 % at and below a wavelength of 410 nm and not exceeding 50 % at a wavelength of 420 nm.
5.4 Two working standards. Two plates of flat opal glass or ceramic or other suitable material, cleaned and calibrated as described in ISO 2469.
NOTE In some instruments, the function of the primary working standard can be taken over by a built-in internal standard.
5.5 Black cavity, having a reflectance factor which does not differ from its nominal value by more than
0,2 % at all wavelengths. The black cavity should be stored upside down in a dust-free environment or
with a protective cover.
NOTE 1 The condition of the black cavity can be checked by reference to the instrument maker. NOTE 2 The nominal value is given by the manufacturer.
6 Sampling and conditioning
If the tests are being made to evaluate a lot of paper or board, the sample should be selected in accordance with ISO 186. If the tests are made on another type of sample, make sure that the test pieces taken are representative of the sample received.
Conditioning according to ISO 187 is recommended but not required, but preconditioning with elevated temperatures should not be applied since it might change the optical properties.
7 Preparation of test pieces
Avoiding watermarks, dirt and obvious defects, cut rectangular test pieces approximately 75 mm x 150 mm. Assemble at least 10 of the test pieces in a pad with their top sides uppermost; the number of test pieces should be such that doubling the number does not alter the reflectance factor. Protect the pad by placing an additional sheet on both the top and bottom of the pad; avoid contamination and unnecessary exposure to light or heat.
Mark the top test piece in one corner to identify the sample and its top side.
If the top side can be distinguished from the wire side, it shall be uppermost; if not, as maybe the case for papers manufactured on twin-wire machines, ensure that the same side of the sheet is uppermost.
8 Procedure
8.1 If the sample contains or may contain a fluorescent whitening agent, check that the 420 nm UVcut-off filter is in the UVex(420) position.
8.2 Remove the protecting sheets from the test-piece pad. Without touching the test area, use the procedure appropriate to the instrument and the working standard to measure the intrinsic luminance factor of the top side of the test-piece pad. Read and record the value to the nearest 0,01 % of the luminance factor.
8.3 Remove the top test piece from the pad and, with the black cavity backing the test piece, measure the single-sheet luminance factor, Ro, for the same area of the test piece. Read and record the value to the nearest 0,01 % of the luminance factor.
8.2 and 8.3 describe the two independent measurements required to calculate the light absorption and scattering coefficients using the Kubelka-Munk theory in Clause 9. This is not intended to imply that the two measurements shall necessarily be made in this order.
8.4 Move the measured test piece to the bottom of the pad. Repeat the measurements of and R,o, moving the top test piece to the bottom of the pad after each pair of measurements, until five pairs of measurements have been made.
This subclause implies that measurements of and R,o shall be made alternately, but this is not an essential requirement of this document. The five measurements of R,o may be made before or after the five measurements of if such a procedure is preferred, or the measurements may be made alternately.AS NZS 1301.545 pdf download.