For decades, the problem with collectible toys has been degradation of the materials. For most toys made in the past 40 years or more the main component is ABS plastic. ABS plastic breaks down and changes color as it ages. This process can be accelerated via exposure to UV rays (sunlight or fluorescent bulbs), Heat,  and chemical reaction to other plastics. Most collectors have fought a losing fight to prevent their lighter colored plastics from turning yellow (or green if there is a blue