Rubber components used outdoors face far harsher conditions than those in controlled indoor environments. Sunlight, ozone, moisture, temperature swings, and atmospheric pollutants can all break down elastomers—leading to cracking, hardening, and premature failure.

This guide from Primo Rubber Co. explains how UV, ozone, and weathering affect different rubber compounds, and how to choose the right material for outdoor applications like gaskets, boots, bumpers, seals, pads, and structural isolation components.

Why Outdoor Environments Destroy Rubber

Rubber degradation outdoors comes primarily from three factors:

1. UV (Ultraviolet) Radiation

UV breaks down polymer chains, causing:

  • Surface chalking
  • Micro-cracking
  • Hardening
  • Loss of elasticity

Black rubber with carbon black filler resists UV extremely well, while light-colored compounds are more vulnerable.

2. Ozone Exposure

Ozone (O₃) in the atmosphere reacts with double bonds in certain elastomers, causing:

  • Surface cracks (often perpendicular to strain direction)
  • Brittleness
  • Material splitting under minor flexing

This is especially destructive in flexing components like boots or bushings.

3. Weathering & Environmental Cycling

Weathering includes:

  • Moisture and standing water
  • Temperature swings and thermal shock
  • Salt spray
  • Airborne pollutants
  • Freeze–thaw cycles

These stressors contribute to long-term aging and mechanical breakdown.

Best Rubber Compounds for Outdoor Use

Below is a breakdown of the most common outdoor-rated elastomers and what environments they perform best in.

EPDM (Ethylene Propylene Diene Monomer)

Best overall outdoor rubber

  • Excellent UV resistance
  • Exceptional ozone resistance
  • Great weathering resistance
  • Performs well in steam, water, and outdoor moisture
  • Poor resistance to oils and fuels

Best for:
Roofing components, seals, HVAC, outdoor gaskets, automotive weatherstripping, water-exposed components.

Silicone Rubber (VMQ & LSR)

Best for extreme temperatures

  • Withstands –60°C to 200+°C
  • Very good UV and ozone resistance
  • Great flexibility even in cold climates
  • Poor abrasion resistance
  • Moderately poor tensile strength compared to EPDM or FKM

Best for:
Lighting gaskets, outdoor electronics, high-heat enclosures, solar equipment.

FKM (Viton®-type Fluoroelastomer)

Best for outdoor oil/fuel exposure

  • Strong UV and weathering resistance
  • Excellent chemical and fuel resistance
  • Great high-temperature stability
  • More expensive than most rubbers

Best for:
Outdoor fuel systems, generators, chemical exposure, aerospace and industrial seals.

NBR (Nitrile Rubber)

Good outdoor performance—if formulated correctly

Standard NBR is not a top performer outdoors, but specialized hydrogenated versions (HNBR) offer:

  • Better UV resistance
  • Better ozone resistance
  • Great oil resistance
  • Good abrasion resistance

Best for:
Outdoor hydraulic systems, machinery boots, agricultural equipment.

Natural Rubber (NR)

Not ideal outdoors

  • Poor UV and ozone resistance without heavy stabilization
  • Excellent mechanical properties
  • Good abrasion resistance

Use only if protected from direct sunlight or treated with coatings.

Tips for Making Rubber Last Longer Outdoors

Regardless of the compound, consider these design strategies:

1. Choose carbon-black–filled black rubber

Carbon black acts as a powerful UV absorber.

2. Add anti-ozonants and wax bloom agents

These form protective surface layers over time.

3. Minimize constant tensile strain in exposed areas

Surface cracks from ozone form perpendicular to strain.

4. Consider coatings or housings

A mechanical shield can dramatically increase service life.

5. Use thicker cross-sections where UV exposure is intense

More material slows through-thickness degradation.

Summary: Which Rubber Should You Choose?

Environment Best Compound
General outdoor exposure EPDM
Extreme temperatures Silicone (VMQ / LSR)
Fuel/oil exposure + outdoor FKM
Outdoor abrasion + oils HNBR
Budget but acceptable performance UV-stabilized NBR

Need Help Selecting the Right Outdoor Rubber?

Primo Rubber Co. specializes in injection molding custom rubber components. Contact Primo Rubber Co. today to discuss your project and find the ideal material and design solution for your rubber parts.