| Popis: |
In the print quality investigations one of the important optical characteristics is the reflectance and opacity of the printed substrate. In this paper the opacity of the recycled and offset substrates by TAPPI 519 has been measured. The method includes d/00 geometry, standard illuminant C and 20 standard observer. The reflectance of a pad, R∞ , for twenty samples, dimension 1cm × 1cm, and the reflectance, R0, of one paper over black background of the reflectance Rg with the reflectance not higher then 0.5% were recorded and were used to calculate opacity values. Measurements of reflectance were made using X-rite Spectrophotometer, Digital Swatchbook, in the interval of the wavelengths from 410nm to 700nm for every 10nm. These measurements were supported by Color Shop 2.0 software and results were calculated by MathCad 2000 and by Data Analysis and Technical Graphics Origin 6.0. The surfaces of the samples were measured in ten different points and statistics of standard deviation and relative error was applied. The reflectance, the opacity and their standard deviations of both substrates were compared. We discuss these differences caused by differences in the measured substrates. |
