Some rubber ages very well indeed. Some doesn't. "Rubber" means lots of different plastics, some of which are very stable and some of which are very unstable.

Some rubber ages very well indeed. Some doesn't. "Rubber" means lots of different plastics, some of which are very stable and some of which are very unstable. Some are natural; others are synthetic. All they have in common is that they are soft and very elastic—if even that, since sometimes ebonite is called a rubber as well, comprised as it is in large part of natural latex rubber. Silicone rubbers in particular are extremely stable.