Also this test relies on the fact that old phenolic plastic must already be degraded. If the plastic is new, or has been recently cleaned, the test will likely not work. The reason that it works sometimes is that old phenolic plastic parts in radios were never manufactured very well. Properly proportioned and cured, Bakelite degrades very little. I really do not understand why it is so difficult for people to identify.
Lower temperature slows any reaction rate.
Naturally you should avoid direct sunlight too because of the ultraviolet present. Indoor lighting is rarely a problem. Very low temperatures can make plastics brittle, and high temperatures can warp them and increase the degradation rate. Note that electrolytic capacitors require a somewhat humid environment to function properly. Thus you have some conflict with storage conditions.