Product Description

LOCTITE® 243™ is designed for locking and sealing threaded fasteners that require normal disassembly with standard hand tools. It cures in the absence of air when confined between close-fitting metal surfaces, preventing loosening and leakage from shock and vibration. Its thixotropic nature reduces migration of liquid product after application to the substrate.

LOCTITE® 243™ cures reliably not only on active metals (e.g. brass, copper) but also on passive substrates such as stainless steel and plated surfaces. It offers high-temperature performance and oil tolerance, tolerating minor surface contamination from cutting, lubrication, anti-corrosion, and protection fluids. It is particularly suited to locking threaded fasteners in equipment such as pumps, gearboxes, motors, and vehicles.

Typical Properties of Uncured Material

Typical Curing Performance

Cure rate depends on substrate, bond gap, temperature, and (where needed) activator use:

• Cure speed vs. substrate: Breakaway strength on M10 steel nuts and bolts (23°C, ISO 10964) develops fastest on active metals like brass, followed by steel, chromium-free zinc organic, and stainless steel, with zinc dichromate developing more slowly.

• Cure speed vs. bond gap: Shear strength on steel pins and collars (23°C, ISO 10123) develops faster at tighter bond gaps (0.05 mm) than at wider gaps (0.15–0.25 mm).

• Cure speed vs. temperature: Higher temperatures (e.g. 40°C) accelerate breakaway strength development on M10 steel nuts and bolts (ISO 10964) compared with 22°C or 5°C.

• Cure speed vs. activator: Where cure speed is too slow or gaps are large, applying Activator 7471™, 7649™, 7088™, or 7091™ accelerates strength development versus no activator, tested on M10 zinc dichromate steel nuts and bolts (ISO 10964).

See the full technical bulletin curves for detailed strength-vs-time data on each condition.

Directions for Use

For Assembly

For best results, clean all surfaces (external and internal) with a LOCTITE® cleaning solvent and allow to dry.

If cure speed is too slow, use the appropriate activator (see Cure Speed vs. Activator data above); allow the activator to dry when needed.

Shake the product thoroughly before use.

To prevent clogging in the nozzle, do not allow the tip to touch metal surfaces during application.

For thru holes: apply several drops of product onto the bolt at the nut engagement area.

For blind holes: apply several drops of product to the lower third of the internal threads, or the bottom of the blind hole.

For sealing applications: apply a 360° bead of product to the leading threads of the male fitting, leaving the first thread free, forcing the material into the threads to fill voids. For larger threads/voids, adjust the amount and also apply a 360° bead on the female threads.

Assemble and tighten as required.

For Disassembly

Remove with standard hand tools.

In rare cases where hand tools do not work due to excessive engagement length, apply localized heat (approximately 250°C) to the nut or bolt and disassemble while hot.