Rubber or Plastic? Picking the Right Washer Material.

Washer material picks run along two axes. Family comes first (rubber vs. plastic), then compound (EPDM or Silicone inside rubber, PTFE or Nylon inside plastic). This guide walks both decisions in order and points you at our product pages for durometer, tolerance, and certification detail.

Step 1: Rubber or plastic?

Start with the function. Pick rubber when the washer has to give. It needs to conform, compress, and recover under bolt load, either to seal or to soak up vibration. Pick plastic when the washer has to hold its shape, isolate a fastener electrically, run a low-friction face, or survive temperature outside the rubber band.

Step 2a: Rubber washer compounds

Inside the rubber family, three things drive the compound pick: fluid exposure, temperature, and regulatory callouts. The table below covers the rubber washer materials we run most often. Click any material to land on its product page for durometer range, standard sizes, and FDA or MIL-spec availability.

Step 2b: Plastic washer compounds

Plastic washers show up for electrical isolation, low-friction bearings, dimensional precision, and temperature extremes. Every compound has its own performance envelope. The table below covers the engineering thermoplastics we convert most often.

Step 3: Durometer, thickness, and tolerance

Compound picked. Now three dimensions.

• Durometer (rubber only): Shore A hardness runs from 30A (soft, happy on a rough mating surface) to 90A (hard, built for high bolt load). Most washer builds land in the 60A to 80A window. The Durometer Chart converts between Shore A, Shore D, and IRHD.
• Thickness:Rubber washers typically run 1/32" to 1/4". Thicker stock fills larger gaps but takes more compression set over time. Plastic washers usually 0.010" to 0.500".
• Tolerance:Standard die-cut tolerance is ±0.015" on OD/ID for rubber, ±0.005" on plastic. Tighter is available if you pay for the tooling. Only spec what the application needs.

Use engineering tools to narrow faster

When to call Cannon Gasket

Standard compounds in standard sizes ship from the category page. Call engineering for any of the following. Cannon Gasket reviews material specs on every RFQ at no charge.

• Regulatory certification beyond the standard grades (FDA lot trace, USP Class VI, MIL-spec, NSF-61)
• Non-standard durometer, thickness, or OD/ID tolerance
• Exotic materials (fluorosilicone, HNBR, Aflas®, UHMW alloys)
• PSA (pressure-sensitive adhesive) backing, pad printing, or custom packaging
• Prototype qualification before committing to a production material

Request a Material Recommendation