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LOCTITE 408 Instant Adhesive for Clean and Fast Component Bonding

LOCTITE 408 Instant Adhesive is a one-component cyanoacrylate developed for rapid bonding where low odor, minimal blooming, and a clean finished appearance are important. Its ultra-clear, very-low-viscosity formulation creates thin bond lines between closely fitting parts and is suitable for metals, plastics, elastomers, wood, paper, leather, and fabric. No separate hardener, mixing process, or external heating is required.

The alkoxyethyl cyanoacrylate chemistry produces less airborne vapor than many conventional instant adhesives. This helps reduce the white frosting commonly called blooming around the bonded area. These characteristics make the product useful for visible assemblies, decorative components, workplace environments where vapor control is difficult, and applications where adhesive appearance affects the quality of the finished product.

Key Benefits of LOCTITE 408 Instant Adhesive

LOCTITE 408 Instant Adhesive has a typical viscosity of only 4–10 mPa·s at 25°C and a specific gravity of approximately 1.1. Its very fluid consistency allows it to wet narrow interfaces, penetrate porous materials, and form thin adhesive films. The current Henkel product information lists gap-filling capability up to approximately 0.15 mm, although the fastest curing and strongest performance normally occur in closely fitted joints.

Fixture speed depends on the substrate, bond gap, temperature, and humidity. Representative fixture times are less than five seconds on aluminum, ABS, neoprene, nitrile rubber, phenolic material, leather, and paper. Typical fixture time is 20–30 seconds on steel, 10–20 seconds on pine, and 20–45 seconds on polycarbonate. Full chemical and solvent resistance continues to develop for at least 24 hours after assembly.

Published strength data includes lap-shear values of approximately 20.8 N/mm² on grit-blasted steel, 17.3 N/mm² on etched aluminum, 9.7 N/mm² on ABS, and 8.6 N/mm² on polycarbonate after 72 hours at 22°C. A representative tensile strength of approximately 27.3 N/mm² is listed for steel pin-to-pin assemblies after 24 hours. These values are typical laboratory results and should be verified using the actual production components.

Applications for LOCTITE 408 Instant Adhesive

LOCTITE 408 Instant Adhesive is suitable for plastic housings, rubber components, metal fittings, electronic parts, decorative assemblies, labels, leather products, wooden components, paper materials, fabric parts, appliances, instruments, and precision industrial products. Its low-bloom performance is especially useful on dark, transparent, painted, polished, or visually exposed components where ordinary cyanoacrylate vapor may leave a white residue.

Compatible substrates include steel, aluminum, ABS, PVC, polycarbonate, phenolic materials, neoprene, and nitrile rubber. Difficult low-surface-energy plastics such as polypropylene, polyethylene, and PTFE may be bonded after applying LOCTITE SF 770 primer. Because plastic formulations vary, adhesion, stress cracking, discoloration, and appearance should be tested before volume production.

How to Apply LOCTITE 408 Instant Adhesive

Clean both bonding surfaces and remove grease, oil, moisture, dust, release agents, and loose contamination. LOCTITE SF 7070 or another compatible cleaner may be used. Apply a small amount of adhesive to one surface only and assemble the parts immediately. Accurate initial positioning is essential because the rapid fixture time provides little opportunity for adjustment.

The best curing results are generally obtained at approximately 40–60% relative humidity and 22°C. Low humidity slows curing, while excessively high humidity may accelerate fixture but reduce final strength. Where a larger gap causes slow curing, LOCTITE SF 7452 or SF 7455 activator may be evaluated, although activators can affect ultimate bond strength.

Storage of LOCTITE 408 Instant Adhesive

Store unopened LOCTITE 408 Instant Adhesive in a dry location between 2°C and 8°C. Do not return dispensed material to the original container. Unopened cyanoacrylate products should be refrigerated, but opened bottles should not be returned to refrigeration and should be used promptly for the best performance.

For manufacturers requiring rapid fixture, nearly invisible bond lines, low odor, and reduced blooming, LOCTITE 408 Instant Adhesive provides efficient one-part bonding for metals, plastics, elastomers, and porous materials. Explore our low-bloom instant adhesives for visible plastic, rubber, metal, leather, wood, paper, and precision-component assemblies.

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