BISCO®HT-6220 Soft Solid Silicone Gaskets

SPECIFIC GRAVITY:
1.08 g/cc
DUROMETER, SHORE A [ASTM D395]:
20
COMPRESSION SET, 70 HOURS @ 302˚F @ 25% [ASTM D395]:
<25%
TENSILE STRENGTH [ASTM D412]:
640 psi
ELONGATION [ASTM D412]:
580%
TEAR RESISTANCE [ASTM D412]:
116 ppi
DIELECTRIC STRENGTH [ASTM D149]:
374 Volts/mil
DIELECTRIC CONSTANT [ASTM D150]:
2.97 kHz
DISSIPATION FACTOR [ASTM D495]:
0.003 kHz
DRY ARC RESISTANCE [ASTM D495]:
123 seconds
VOLUME RESISTIVITY [ASTM D257]:
10^14 Ohm-cm
THERMAL CONDUCTIVITY [ASTM D518]:
0.22 W/m˚K

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Product Overview

BISCO® HT-6220 — Extra-Soft Solid Silicone — Technical Overview & FAQs

Product Overview

BISCO® HT-6220 is an extra-soft, solid silicone rubber (20 Shore A) designed for applications that require gentle compression and reliable environmental sealing.
Its low-durometer formulation provides superior flexibility, sealing performance at low clamp loads, and long-term resilience against heat, ozone, and UV exposure.
HT-6220 maintains elasticity from sub-zero to elevated temperatures, making it a preferred choice for lighting, electronics, and aerospace gaskets that need compliant sealing under minimal pressure.

Applications

Low-compression environmental gaskets and door/panel seals
Sensitive electronics, lighting, and instrumentation enclosures
Aerospace and defense equipment needing vibration isolation
Industrial and medical assemblies requiring soft, non-toxic elastomers
Die-cut or kiss-cut gaskets and PSA-backed sealing strips

Key Properties

Shore A Hardness: 20 ± 5
Specific Gravity: 1.10 g/cc
Tensile Strength: ≈ 900 psi
Elongation at Break: ≥ 750 %
Compression Set (70 h @ 302 °F): ≤ 25 %
Operating Temperature Range: –80 °F to 450 °F (–62 °C to 232 °C)
Weather, Ozone, and UV Resistance: Excellent
Fluid Resistance: Moderate to good against water, oils, and coolants
Compliances: A-A-59588, AMS 3301–3305, FDA 21 CFR 177.2600, NSF 51

FAQs

What is BISCO HT-6220 used for?
It’s a very soft, solid silicone rubber used for low-pressure sealing, gasketing, and vibration damping where delicate or uneven surfaces require gentle compression.

What makes HT-6220 different from other silicones?
Its 20 Shore A softness offers maximum conformability and sealing performance under minimal clamp force — ideal for fragile assemblies or lightweight structures.

Can HT-6220 withstand extreme temperatures?
Yes — it retains elasticity and seal integrity from –80 °F to 450 °F (–62 °C to 232 °C), with excellent thermal stability and low compression set.

Is HT-6220 suitable for outdoor or UV exposure?
Absolutely. It exhibits superior resistance to UV, ozone, and weathering for long-term outdoor applications.

Can HT-6220 be customized or adhesive-backed?
Yes — it can be supplied as sheets, rolls, or die-cut gaskets with optional silicone or acrylic PSA for easy peel-and-stick assembly.

Request BISCO® HT-6220 samples, spec data, or custom die-cut gaskets from H-O Products for your next low-compression sealing project - contact us.