BISCO® HT-840 – Extra Firm Silicone


BISCO® HT-840 – Extra Firm Cellular Silicone For Custom Gaskets and Seals

BISCO® HT-840 is an extra-firm grade silicone foam that offers improved durability and sealing. It is used to seal and protect various outdoor communication, lighting, and electronic enclosures from small dust particles, wind driven rain, and fire. It offers a higher tear and tensile strength than our lighter grade foams. BISCO® Silicones are available in various thicknesses and manufactured in roll form to allow fabricators to easily convert the material to the proper dimensions.

Available Thickness0.063″ – .250″
Typical Density28 lb/ft3
CFD Range16-26 psi
SpecificationsUL94 V-0 and HF-1
GradeExtra-Firm Silicone Foam

Features and Benefits of  BISCO® HT-840

  • Excellent memory and low stress relaxation reduces maintenance costs associated with gasket failures due to compression set and softening.
  • Resistance to ultraviolet light, ozone, extreme temperatures, and flame enables consistent performance in all environments.  Compact cell structure provides improved sealing performance.
  • Available through distribution sites throughout North America, Europe, and Asia.


  • Environmental seals to protect against penetration of dust, moisture, air, or light within outdoor enclosures such as lighting fixtures, HVAC units, and electronic cabinets
  • Enclosures requiring a more durable, high closure force gasket.
  • Press pads requiring greater conformability and even pressure distribution at high temperatures


  • Available with a pressure-sensitive adhesive on one or two sides to allow easy application to a variety of surfaces.

Application Bulletins and Articles


Data Sheets

Technical Literature

SRP: A Rogers Corporation Preferred Converter

SRP is proud to be a Rogers Corporation Preferred Converter for their line of PORON® Polyurethane and BISCO® Silicone materials. We provide distribution and converting of these materials to various industries and customers around the world. Being a Preferred Converter for Rogers provides us access to all Rogers materials, with the added benefit of discounts and favorable lead times. SRP converts these materials in custom gaskets, seals, pads and stripping. All products can be laminated with a pressure sensitive adhesive.