Velvia 50 exposed to high temperatures will lose depth in the primaries, especially red and green. The real test is exposing it in light for which it was not designed for and examining the reaction of the emulsion to the extreme of contrast. On the other hand, if it is exposed in diffuse or soft light (its design intent), one may well arrive at the conclusion that it has come through the storage unscathed. Its tolerance for high temperature is especially poor and degradation does occur.