Choosing the right rubber washer starts with choosing the right material. A washer that's perfect for a fuel line can fail within days outdoors, and one that shrugs off sunlight may swell and dissolve the moment it touches oil. This guide breaks down the seven compounds we stock so you can match the material to the job the first time.
Quick comparison of rubber washer materials
| Material | Temp range | Best for | Avoid |
|---|---|---|---|
| Neoprene | -50°F to 250°F | All-purpose sealing, weather, refrigerants | Strong acids, fuels |
| EPDM | -40°F to 300°F | Outdoor, water, steam, ozone | Petroleum oils & fuels |
| Nitrile (Buna-N) | -40°F to 250°F | Oil, fuel, hydraulic fluid | Sunlight, ozone |
| Silicone | -80°F to 450°F | Extreme temperatures, food & medical | Abrasion, fuels |
| Natural Rubber | -40°F to 180°F | Shock, vibration, abrasion | Oil, ozone, sunlight |
| Viton (FKM) | -15°F to 400°F | Aggressive chemicals, fuel, high heat | Low-temperature flexibility |
| Fiber | up to 250°F | Dry gasketing, plumbing fittings | Continuous water immersion |
Material-by-material breakdown
Neoprene
The do-everything compound. Neoprene balances weather, ozone and moderate chemical resistance, which makes it the default choice when you're not sure what you need. It's a workhorse for HVAC, automotive trim and general sealing.
EPDM
The outdoor champion. EPDM laughs at sunlight, ozone, rain and steam, and it's a common choice for potable water. Its one weakness is petroleum: keep it away from oils, fuels and grease.
Nitrile (Buna-N)
The oil specialist. If your washer will see motor oil, diesel, gasoline or hydraulic fluid, nitrile is the answer. Just don't leave it in direct sun, where it cracks over time.
Silicone
The temperature extremist. Silicone stays flexible from cryogenic cold to 450°F and is food- and medical-safe, but it tears more easily than other rubbers and dislikes fuels.
Natural Rubber
The shock absorber. Unbeatable for vibration, impact and abrasion, natural rubber is ideal for mounts and pads — but it degrades with oil, ozone and UV.
Viton (FKM)
The chemical fortress. Viton resists aggressive acids, fuels and high heat that destroy other rubbers. It's premium-priced, so reserve it for jobs that truly need it.
Fiber
The dry-seal gasket. Fiber washers seal threaded plumbing and fuel fittings where a firm, compressible dry gasket beats a soft rubber.
How to choose in three questions
- Will it see oil or fuel? Choose Nitrile or Viton, never EPDM or natural rubber.
- Will it live outdoors? Choose EPDM or Neoprene for UV and ozone resistance.
- How hot or cold? Past 250°F, move to Silicone or Viton.
Once you've picked a compound, use our rubber washer size guide to dial in the dimensions, then browse the full rubber washer catalog — every size ships in all seven materials.