Is hard rubber stable?
Hard rubber is in many respects one of the most stable plastics, old or new. It does not shrink as it ages, nor does it outgas plasticizers. Exposure to bright light and especially UV may cause dulling and fading of the surface, but this does not affect the integrity of the object as a whole. Rubber chemistry, including hard rubber chemistry, has not stood still over the past 150 years. Modern hard rubbers are significantly more resistant to light fading than their early 20th-century precursors.
