EVERYDAY MATERIALSAtlas
Making a resilient seal

Natural rubber or silicone rubber for a seal?

Elastomers stretch because their long molecular chains can change shape. Crosslinks help them recover. Their exact recipe, hardness and curing matter; the family name alone cannot establish compatibility with a liquid or temperature.

On a phone, each design question stacks the material choices for easier reading.

Qualitative comparison · Grade, shape and operating conditions can change these tendencies.
Design questionNatural rubberSilicone
StructureA carbon-based polymer obtained from latex, usually compounded and crosslinked.A silicon–oxygen backbone with organic side groups; usually formulated and cured.
StrengthsUseful elasticity, resilience and mechanical performance in suitable compounds.Useful flexibility over a broad temperature range in suitable formulations.
LimitsOzone, heat, oils or ageing can cause trouble depending on the compound.Tear resistance, abrasion and fluid compatibility need application-specific checks.
After useVulcanised rubber cannot simply be melted like a thermoplastic.Crosslinked silicone also needs specialised recovery routes.

What changes the answer?

A seal that looks the same can behave very differently. Replacement parts should match the application specification, not just the colour or apparent softness.

Follow the evidence

Original explanations informed by the sources below. Technical and industry sources support material behaviour; industry environmental marketing is not treated as a universal comparison. Read our editorial method.