O-ring elastomers
The base polymer of an elastomeric compound is called rubber. That may be a natural rubber or, more commonly today, a synthetic rubber.
An elastomeric compound typically contains 50-60% of a base polymer with the remainder consisting of various fillers, vulcanising agents, accelerators, ageing retardants and other chemicals that modify the physical properties of the base polymer to suit specific applications.
O-rings are available in the following compounds:
| Nitrile 70 & 90 Durometer | Fluorosilicone |
| Viton® 75 & 90 Durometer | PTFE |
| Neoprene | FEP Encapsulated Viton & Silicone |
| EPDM | Aflas® |
| Silicone | Kalrez® - perfluoroelastomer |