A technical choice: the gasket raw materials

The material was not chosen in regards of its price or ease of molding like gaskets made of PU foam injected through the process “Formed in place foam gasket or FIPFG “, or even of the possibility of die-cutting, but to meet the technical requirements of electrical heating applications: heat resistance, fire resistance, mechanical resistance to successive openings and closings, UV resistance.

Comparison chart of the common materials used for housing gaskets
(Compared with equivalent density of 2.4 g/cm3 and equivalent hardness of 12 to 18 Shore A)


Material Minimum using
(ASTM D 746)
permanent using
(SAE J-2236)
distortion after
(ASTM D1056)
Breakage mechanical
Fire resistance
UV resistance
(SAE J1960=
Automotive Industry)
UL508 : boxes
Required force for
a 25% compression
(ASTM D1056)
Polyurethan foam -20°C +90°C < 5% 455KPa (ASTM D3574, test E) HBF
(the lowest class)
Medium deterioration 76 kPa
Silicone foam -55°C +200°C < 5% 246Kpa (ASTM)
V0 and HF1
(the highest class)
No deterioration 27 kPa: the smallest
constraint to close a
lid or a window

Average values for general comparison only as characteristics may vary from a supplier to another.