Shop fiber rubber washers in every OD, ID and thickness we stock. Fiber is rigid, compressible and electrically insulating — making it the go-to choice for electrical insulation, plumbing joints, drain plugs and light-duty sealing. Rated for up to 250°F. Fast shipping and bulk pricing on every order.
Not sure if Fiber is right for your job? Read our Fiber material guide for a full compound comparison, or compare all 7 washer materials side by side. New to washer sizing? See how to measure OD, ID & thickness, then shop the full catalog.
Popular Fiber uses: electrical & electronics and plumbing.
Fiber washer properties
| Property |
Rating |
| Temperature limit |
Up to 250°F continuous |
| Structure |
Vulcanized cellulose fiber — semi-rigid, compresses slightly, doesn't flow |
| Electrical insulation |
Excellent — a classic insulating washer material |
| Oil & fuel |
Good — traditional for drain plugs and fittings |
| Water |
Fair — absorbs moisture in continuous immersion |
| Torque handling |
Excellent — won't extrude under high clamp loads like soft rubber |
Fiber vs rubber washers: which do you need?
A fiber washer (also spelled fibre washer) behaves halfway between a rubber washer and a metal one. It compresses just enough to seal machined faces — oil drain plugs, compression fittings, gas appliance unions, carburetor banjo bolts — while holding torque that would squeeze a soft rubber washer out of the joint. It's also a first-rate electrical insulator and anti-galvanic spacer between dissimilar metals. Choose soft rubber (EPDM, neoprene) when surfaces are rough or the seal must conform; choose fiber when surfaces are machined flat and clamping force is high. See where fiber sits on the hardness spectrum in the durometer guide.
Fiber washer FAQ
What are fiber washers made of?
Vulcanized cellulose fiber — cotton-based material chemically treated into a dense, tough, semi-rigid sheet, then die-cut into washers.
Are fiber washers good for oil drain plugs?
Yes — fiber is one of the traditional drain plug washer materials: oil-resistant, crush-seals once, and holds torque. Replace it at each oil change; they're single-compression parts.
Can fiber washers be reused?
Best practice is no — the seal comes from a one-time crush. Reuse risks a slow weep on oil pans and fittings.
Fibre washers and fiber washers — same thing?
Yes, just US vs UK spelling of the same vulcanized fiber washer.
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