D1115M
70 Shore A General Purpose Solid Silicone
BISCO® HT-1270 is a 70 ±5 Shore A solid silicone elastomer engineered for applications requiring maximum firmness and reduced material deflection under sustained compression and elevated temperature exposure. Rated from −80°F to 425°F, HT-1270 maintains ≤25% compression set after 70 hours at 302°F, supporting reliable sealing performance in high-load environments.
Key Properties
- Hardness: 70 ±5 Shore A
- Tensile Strength: 1050 psi
- Elongation: ≥125%
- Compression Set: ≤25% (70 hrs @ 302°F, 25%)
- Specific Gravity: 1.29 g/cc
- Recommended Service Temperature: −80°F to 425°F
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Physical Properties
Property Value Test Method Material Solid Silicone — Specific Gravity 1.29 g/cc ASTM D2240 Thicknesses Available 0.031″, 0.063″, 0.094″, 0.125″ — Colors Red, Black, Gray, White — Mechanical Properties
Property Value Test Method Durometer 70 ±5 Shore A ASTM D2240 Tensile Strength 1050 psi ASTM D412 Elongation ≥125% ASTM D412 Compression Set (70 hrs @ 302°F, 25%) ≤25% ASTM D395 Heat Aging Performance
(70 Hours @ 437°F)
Property Change Value Test Method Hardness Change ±10 pts ASTM D573 Tensile Change −20% ASTM D573 Elongation Change −40% ASTM D573 Oil Immersion Performance
(70 Hours @ 302°F)
Property Change Value Test Method Hardness Change −10 to +5 pts ASTM D471 Tensile Change −10% ASTM D471 Elongation Change −15% ASTM D471 Volume Change +5% ASTM D471 Environmental Performance
Property Value Test Method Low Temperature Brittleness Pass ASTM D2137 Recommended Use Temperature −80°F to 425°F — Compliance
- A-A-59588 — Compliant
- AMS 3301–3305 — Compliant
- FDA 21 CFR 177.2600 — Compliant
- NSF 51 — Compliant (File MH62230)
- A-A-59588 — Compliant
- Various high and medium surface energy plastics
- Glass
- Steel
- Aluminum
- Ceramics
Common industries: aerospace, automotive, electronics, industrial equipment, and regulated processing environments.
HT-1270 is the firmest grade within the HT-1200 series, designed for applications requiring high rigidity and minimal compressive deformation. Its 70 Shore A hardness provides increased structural support while maintaining predictable compression retention and thermal stability.
The material demonstrates controlled mechanical change after heat aging and oil immersion testing, supporting use in industrial environments exposed to sustained thermal cycling and fluid contact.
Compliant with A-A-59588, AMS 3301–3305, FDA 21 CFR 177.2600, and NSF 51.
What differentiates HT-1270 from other HT-1200 grades?
HT-1270 is the firmest grade at 70 Shore A, providing the highest resistance to deformation under compressive load.
Why is compression set critical?
Compression set measures long-term recovery after sustained compression. Lower values support improved sealing retention over time.
What is the operating temperature range?
−80°F to 425°F.
Is HT-1270 suitable for regulated environments?
Yes. It complies with aerospace and food-contact related standards listed above.
How should this material be specified?
Specify grade (HT-1270), thickness, color, compliance requirements, dimensional tolerances, and finished format.