This procedure is used to determine the amount of haze and the degree of color exhibited by a preform or container sidewall. This is an indication of how effectively the material was processed and/or the material’s ability to be processed.
The samples are measured in terms of L*, a*, b*, DE* and Haze: L* (100=white; 0=black), a* (positive=red; negative=green; 0=gray), b* (positive=yellow; negative=blue; 0=gray), DE is a mathematical equation which takes into account the values of L*, a* and b*. Haze measures the scattering of light through the sample; the higher the number the more haze. The haze can be used as an indicator of the presence of crystallinity in the sample.