Henkel LOCTITE AA 349 UV Cure Glass Adhesive for Optical Instruments

LOCTITE AA 349 UV Cure Glass Adhesive Performance

LOCTITE AA 349 uses ultraviolet light to initiate curing, allowing operators to dispense and accurately position components before exposing the joint to the curing lamp. Henkel specifies curing with 365 nm ultraviolet radiation. For exposed adhesive surfaces requiring a dry, tack-free finish, radiation near 250 nm is also required. A typical reference cure is approximately 20 to 30 seconds at 100 mW/cm² using a medium-pressure mercury-vapor lamp.

The product has a typical specific gravity of 1.02 and a Brookfield viscosity range of approximately 6,000 to 13,500 mPa·s at 25°C. This medium-viscosity profile helps the adhesive wet prepared surfaces while remaining controllable around narrow edges, circular joints, glass fittings, and precision metal inserts. Because it is supplied as a single component, no resin-and-hardener measuring, mixing, or ratio control is required.

Fast UV Curing for Glass and Metal Assembly

Fixture speed depends on UV intensity reaching the adhesive. Henkel reports a glass fixture time of approximately three to eight seconds at 10 mW/cm² and one to five seconds at 100 mW/cm², measured at 365 nm. The typical tack-free time is approximately five to ten seconds at 100 mW/cm². Actual curing performance depends on lamp spectrum, intensity, distance, adhesive depth, bond-line gap, exposure duration, and the light transmission of the substrate.

LOCTITE AA 349 UV Cure Glass Adhesive is intended for bonding and sealing glass to itself or to compatible metal components. Typical applications include precision optical instruments, glass furniture, display structures, decorative glass assemblies, laboratory equipment, lighting components, industrial devices, and selected electronic products. Its electrical insulation properties also make it suitable for evaluated potting and component-tacking applications.

7 Benefits of LOCTITE AA 349 UV Cure Glass Adhesive

• Rapid UV curing: Supports short fixture times and high-speed production processes.
• Transparent appearance: Produces visually clean bonds in glass and decorative assemblies.
• One-component processing: Eliminates weighing, manual mixing, and ratio-control errors.
• Medium viscosity: Supports accurate dispensing without excessive uncontrolled flow.
• Glass and metal adhesion: Designed for glass-to-glass and glass-to-metal components.
• Electrical insulation: Suitable for evaluated potting and electronic tacking applications.
• On-demand curing: Allows component positioning and inspection before UV exposure.

Mechanical and Electrical Properties

After curing, the adhesive provides a typical Shore D hardness of approximately 70. Henkel reports volume resistivity of about 5 × 10¹⁵ ohm-cm and dielectric breakdown strength of approximately 90 kV/mm under the referenced test methods. These electrical characteristics support use around properly designed electrical and electronic assemblies where a non-conductive bonding or potting material is required.

Published adhesive testing reports tensile strength of approximately 11 MPa for a grit-blasted steel pin bonded to glass after curing for 40 seconds at 100 mW/cm². Torsional shear testing on an aluminum hexagonal button bonded to glass reports at least 70 N·m after the specified UV cure and room-temperature post-cure. Actual strength depends on substrate condition, surface preparation, adhesive thickness, joint design, and curing process.

Applying LOCTITE AA 349 UV Cure Glass Adhesive

Ensure all bonding surfaces are clean, dry, and free from grease, oil, dust, fingerprints, moisture, release agents, and polishing residue. Protect the uncured product from daylight, ultraviolet radiation, and strong artificial lighting. Henkel recommends dispensing through black or fully light-blocking feed lines to prevent premature curing inside the equipment.

Apply the required amount to one surface, assemble and align the components, and expose the complete adhesive area to a validated UV source. Henkel recommends a minimum intensity of 40 mW/cm² at the bond line and exposure for approximately four to five times the measured fixture time. Exposed adhesive surfaces generally require an intensity of around 100 mW/cm² for a dry cure.

Provide cooling when bonding temperature-sensitive thermoplastics and evaluate plastic grades for possible stress cracking. Allow the bonded assembly to cool before applying service loads. Store unopened containers in a dry location between 8°C and 21°C, and never return dispensed or potentially contaminated material to the original package.

Official Resources and Related Light-Curing Adhesives

Review the official Henkel LOCTITE AA 349 product page and the official LOCTITE AA 349 technical data sheet for current properties, curing recommendations, storage guidance, packaging, and safety documentation.

Explore our UV-curable glass adhesives for additional transparent glass-bonding products. Browse our optical assembly adhesives for lenses, instruments, sensors, displays, lighting components, and precision devices. Contact our sales team for quotations, 50 ml or regional package availability, technical documents, curing-equipment guidance, bulk quantities, and export support.