Лако-красочные материалы — производство

Transparency is expressed quantitatively as the transparency number. This is defined as the reciprocal of the increase in color difference AE* ab = 1 on a black substrate obtained on increasing the film thickness h of the pigmented medium. The trans­parency number has the unit mm (= L m-2). It indicates the number of liters of pigmented medium needed to coat 1 m2 of a black substrate in order to obtain a color difference of ДЕ*ab = 1 relative to this substrate. In a simplified method the transparency number can be determined by evaluating one or two points on the straight part of the ДЕ *ab (h) curve. A computer method is more exact; furthermore, calculations can be made using the spectral “principle of spectral evaluation.” For standards, see Table 1.1 (“Transparency”).

1.4