LOCTITE EA 9377 AERO (Hysol) epoxy liquid shim for assembling composite units

Country: · Model: EA 9377 AERO

EA 9377 is a two-part thixotropic epoxy paste for a molded plastic shim between composite parts. It fills gaps under 3 mm and works up to 93 °C. It is applied when assembling wings, tail units and fuselage panels.

Type: 2K thixotropic epoxy paste, a molded plastic shim
Cure: dual, at room temperature and with heating
Operating temperature: up to 93 °C
Purpose: gaps < 3 mm and fitting of large areas between composite parts

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Technical specifications

Type	2K thixotropic epoxy paste, a molded plastic shim
Cure	dual, at room temperature and with heating
Operating temperature	up to 93 °C
Purpose	gaps < 3 mm and fitting of large areas between composite parts
Properties	high compressive and peel strength, resistance to microcracking during thermal cycling, CTE matching with composites
Other shims	EA 9394 (compression 68.9 MPa), EA 9360; per the brochure compression 68–78 MPa
Packaging	standard cartridge (A and B 6 oz each)
Qualification	qualified by most commercial aircraft OEMs (per the brochure)

Specifications are taken from the manufacturer’s technical documentation. Updated 11/10/2026.

Description

The liquid shim is applied to one of the parts, for example a rib, the parts are pressed together and drawn tight with fasteners. The excess is squeezed out, so exactly as much material remains in the joint as the gap needs. The paste has dual cure, at room temperature and with heating, high compressive and peel strength and resistance to microcracking during thermal cycling. It matches the difference in thermal expansion on composite substrates. It is supplied in standard cartridges, components A and B 6 oz each. The liquid shim reduces mechanical fitting, removes stress concentration and gives a tight fit, which matters for the fatigue life of bolted and bonded-mechanical joints.

How to choose

If service is above 93 °C, look at the EA 9394 pastes with 68.9 MPa compressive strength and operation up to 177 °C, or EA 9360 with high peel strength above 107 °C. They also work as a liquid shim. Per the brochure the compressive strength of the shims is 68–78 MPa, and the compressive modulus is 2538–2950 MPa.