some info from the technical data sheet
HYLOMAR AEROGRADE (PL32)
Aerospace version of Universal Blue
Description
Hylomar Aero Grade is a highly engineered, polyester-urethane based non-setting and non-hardening
gasketing compound, for use in the aeronautical industry. Hylomar Aerograde was developed in
conjunction with Rolls Royce - Aerospace Division for sealing joints in jet turbine engines. Hylomar
Aero Grade can operate at temperatures from approximately –50°C to + 250°C.