Studies on Influence of Rays upon Film-packing-III

Discoloration of the Film-packed “Sakura-dembu” Stored at Room Temperature

Abstract

In the preceding report, the authors described the discoloration of the film-packed “sakura-dembu” by irradiation with ultraviolet ray for one hour, and discussed the possible main causes of the phenomenon.
In this report, the authors observed the discoloration of the filmpacked “sakura-dembu” which have been storaged at room temperature under natural conditions for one month and compared it with that irradiated with ultraviolet ray using a fade-meter. The discoloration caused under the natural conditions was similar to that caused by irradiation.
However, the discoloration of the samples packed with three kinds of packing films, having different permeabilities against oxygen and ultraviolet rays was nearly similar to ond another after storage for one month. No protective effect was found with the films treated to prevent solar ultraviolet ray.
The strongest discoloration was found with the samples colored with Red 104 and the next those with Red 103. Only a slight discoloration was observed with those colored with Red 106 or with Yellow 4.
The samples colored with a single dye underwent discoloration only when stored under natural conditions. Only a slight discolorations was observed when stored at either room temperature or at refrigeration temperature and protected from light.
Less discoloration was observed with the samples containing 10% moisture than those with 15%, after storage under the same natural conditions for one month.