LOCTITE EA 3421 Epoxy Adhesive is a two-component, high-strength structural bonding system designed for metals, ceramics, wood, glass, rigid plastics, and other compatible industrial substrates. After the resin and hardener are mixed, the adhesive forms a clear amber-yellow material with medium viscosity, useful gap-filling capability, and a long working life. It cures at room temperature and is especially suitable for large bonding areas, rough surfaces, poorly fitting components, or assemblies that need additional positioning and adjustment time.

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LOCTITE EA 3421 Epoxy Adhesive Benefits

LOCTITE EA 3421 Epoxy Adhesive combines high bond strength with excellent moisture resistance and practical processing flexibility. Its 1:1 mix ratio by volume simplifies cartridge dispensing and manual preparation, helping operators achieve a consistent blend without complicated measuring equipment. A 100:90 resin-to-hardener ratio by weight can also be used for bulk applications.

The mixed adhesive remains workable for approximately 30 to 150 minutes at 25°C, depending on the amount prepared and ambient conditions. This extended working life provides time to spread adhesive over large panels, align complex components, and make corrections before the material begins to set. The medium-viscosity consistency flows sufficiently to wet uneven surfaces while remaining controlled during application.

Applications for LOCTITE EA 3421 Epoxy Adhesive

This general-purpose structural epoxy is suitable for bonding steel, stainless steel, aluminum, brass, ceramics, glass, hardwood, softwood, polycarbonate, ABS, phenolic materials, and glass-reinforced plastic after suitable qualification. Typical uses include aluminum window frames, GRP panels, equipment housings, decorative assemblies, industrial furniture, machine components, brackets, covers, panels, and mixed-material structures.

Its gap-filling behavior is valuable where surfaces are rough or do not fit perfectly. The adhesive can distribute loads across the bonded area and reduce the need for screws, rivets, or welding in selected designs. Because surface treatments, coatings, plastic grades, and operating environments vary, every production application should be validated with the actual parts.

LOCTITE EA 3421 Epoxy Adhesive Technical Performance

The resin is a white to off-white paste, while the hardener is a clear amber liquid. When mixed correctly, they produce a clear amber-yellow adhesive. Fixture time is approximately four hours at 22°C, and high strength develops at room temperature within about 36 hours. Elevated temperatures can accelerate curing when the process has been tested and approved.

After seven days of curing at 22°C, published physical properties include Shore D hardness of 70 to 80, tensile strength of approximately 28 N/mm², elongation of about 6%, and compressive strength near 69 N/mm². Typical lap-shear strength on grit-blasted steel is 20 to 25 N/mm². The adhesive also demonstrates resistance to moisture and maintains useful performance across demanding industrial temperatures.

How to Apply LOCTITE EA 3421 Epoxy Adhesive

Clean, dry, and degrease all bonding surfaces. Abrasion or another suitable surface treatment may improve strength and durability. Dispense equal volumes of resin and hardener and mix thoroughly until the appearance is uniform. When using a dual cartridge, attach the correct static mixer and discard the first 3 to 5 cm of material to confirm balanced flow.

Apply the mixed adhesive promptly to one surface, or to both surfaces when maximum coverage is needed. Assemble the components immediately and keep them securely positioned throughout curing. Higher temperatures and larger mixed quantities shorten the working time, so avoid preparing excessive batches. Remove uncured residue before it hardens and allow the joint to develop full strength before service loading.

Why Buy LOCTITE EA 3421 Epoxy Adhesive?

LOCTITE EA 3421 Epoxy Adhesive offers high structural strength, moisture resistance, long working time, room-temperature curing, and dependable bonding across many rigid materials. It is a practical choice for manufacturers, fabricators, maintenance teams, and assembly operations requiring a versatile epoxy for large surfaces, adjustable joints, and uneven components.

Review the current official Henkel Technical Data Sheet and Safety Data Sheet before qualification, storage, handling, or production use. Explore our structural epoxy adhesives for additional metal, glass, ceramic, plastic, wood, and composite bonding solutions.