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HT840 Flame Retardant Silicone Sponge Sheet

HT840 flame retardant silicone sponge sheeting (extra-firm density). This grade offers excellent sealing and durability with a higher tear and tensile strength than lighter grades. 

Its memory and low stress relaxation makes it an excellent gasketing material and its resistance to UV, Ozone and extreme temperatures allow use in all environments. HT840’s cell structure prevents penetration by fine particles and rain. 

This material is suitable for press pads requiring greater conformability and even pressure distribution at high temperatures. Other applications include, but are not limited to gaskets, anti-vibration/cushioning, HVAC systems, anti-fogging seals and battery pads/cushions in the automotive industry.

This sheeting is 915mm wide and sold by the metre.

104,02 Inc. VAT 104,02 Ex. VAT


We can produce this product in almost any size or colour. If you can't find what you're looking for enquire now

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Details & Specs


BISCO HT-840 Extra Firm Cellular Silicone is a very firm grade silicone foam that offers superior sealing capabilities. HT-840 silicone provides a higher tear and tensile strength than our lighter grade foams. HT-840 silicone is designed for use in enclosures requiring a more durable, high closure force gasket. This material is also ideal for use in press pads requiring greater conformability and even pressure distribution at high temperatures. HT-840 silicone is a great choice for sealing and protecting outdoor communication, lighting and electronic enclosures from small dust particles, wind-driven rain and fire.


  • Compact cell structure
  • Available in thicknesses from 0.063 to 0.250 in.
  • Typical density of 28 PCF
  • CFD range of 16-26 PSI
  • Resistant to UV, ozone, extreme temperatures and flame


  • Provides enhanced durability and sealing performance
  • Offers consistent performance in all environments
  • Reduces maintenance costs associated with gasket failures due to compression set and softening


Chemical Resistance

Availability and Fabrication Possibility

  • can be water jet cut or punched into gaskets
  • UL94V0 Compliant for usage were flame retardancy is needed
  • Certified for use in Railway or Aerospace applications
  • PSA Options available
  • Can meet IP Class certifications
  • Automotive, HVAC, LCD and LED Display applications

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