Loctite 243 Threadlocker - 50ml

LOCTITE 243 is a medium-strength, general-purpose anaerobic threadlocking adhesive designed to secure threaded fasteners and prevent loosening caused by vibration, shock and thermal expansion or contraction. It is a versatile threadlocker suitable for a wide range of industrial maintenance, automotive and mechanical assembly applications.

LOCTITE 243 is particularly useful where reliable thread locking is required but the fastener may need to be disassembled using conventional hand tools. It is formulated with improved oil tolerance compared with many conventional threadlockers and can be used on a wide range of metal fasteners, including stainless steel and plated surfaces.

Key Features

Medium-strength threadlocker

Anaerobic curing technology

Designed to prevent loosening from vibration and shock

Suitable for a wide range of threaded fasteners

Good resistance to common industrial oils

Suitable for active and passive metals

Can be used on stainless steel and plated fasteners

Allows subsequent disassembly with normal hand tools

Helps seal threads against leakage and corrosion

One-component liquid formulation

Suitable for industrial assembly and maintenance

Typical colour: Blue

Typical Applications

LOCTITE 243 is suitable for securing threaded components used in:

Bolts and nuts

Screws

Studs

Threaded fittings

Pumps

Motors

Gearboxes

Compressors

Valves

Industrial machinery

Automotive components

Mechanical equipment

General maintenance and repair

It is particularly useful where vibration may cause conventionally tightened fasteners to loosen during service.

How LOCTITE 243 Works

LOCTITE 243 is an anaerobic adhesive. When applied to a threaded metal joint and the fastener is assembled, the adhesive becomes confined between the mating threads. In the absence of air, it polymerizes and forms a strong thermoset plastic that locks the threads together.

The cured adhesive fills the microscopic gaps between the threads, helping prevent relative movement while also improving sealing and corrosion protection within the threaded joint.

Medium-Strength Threadlocking

LOCTITE 243 is classified as a medium-strength threadlocker.

This makes it suitable for applications where:

The joint must resist vibration and loosening.

Reliable locking is required during service.

Future maintenance or disassembly may be necessary.

Conventional hand tools can be used for removal.

Compared with a high-strength threadlocker such as LOCTITE 271, LOCTITE 243 is generally selected when a balance between threadlocking performance and serviceability is required.

Oil-Tolerant Formulation

One of the important features of LOCTITE 243 is its ability to tolerate minor amounts of industrial oils on properly prepared fasteners.

However, for maximum performance, surfaces should still be cleaned and degreased before application. Oil, grease, dirt and other contamination can affect the final strength of an adhesive joint.

Suitable Metals

LOCTITE 243 can be used on a broad range of metal fasteners, including:

Carbon steel

Mild steel

Stainless steel

Zinc-plated fasteners

Nickel-plated surfaces

Other plated or passive metal surfaces

For highly passive surfaces or applications requiring faster cure, an appropriate activator may be considered according to the manufacturer's technical recommendations.

Typical Performance

Typical technical characteristics of LOCTITE 243 include:

Property

LOCTITE 243

Product type: Threadlocker

Strength: Medium

Technology: Anaerobic

Chemical type: Dimethacrylate ester

Colour: Blue

Viscosity: Medium

Cure mechanism: Anaerobic

Application: Threadlocking

Substrates: Metal fasteners

Disassembly: Removable with hand tools

Typical use: Bolts, nuts, screws and studs

Actual technical values can vary by product version and market, so the latest Henkel technical data sheet should be used for specification-critical applications.

Application Procedure

1. Clean the Threads

Remove dirt, grease, oil and other contaminants from the male and female threads where practical.

2. Apply LOCTITE 243

Apply a small amount of adhesive to the threaded area. For through-hole applications, applying the product to the bolt rather than the hole generally provides better control.

3. Assemble the Fastener

Install and tighten the fastener to the required torque while the adhesive is still liquid.

4. Allow to Cure

Leave the assembly undisturbed until sufficient handling and functional strength has developed.

5. Return to Service

Allow the adhesive to reach the required strength before exposing the joint to full operating loads.

Thread Sealing and Corrosion Protection

In addition to locking the fastener, LOCTITE 243 can help fill the clearance between mating threads. This can reduce the potential for leakage through threaded joints and help protect the enclosed thread surfaces from environmental exposure.

However, for dedicated pipe-thread sealing applications, a purpose-designed LOCTITE thread sealant should normally be selected instead.

Industrial Applications

LOCTITE 243 is widely suited to applications involving:

Industrial machinery

Automotive equipment

Pumps and motors

Gearboxes

Compressors

Valves

Mechanical assemblies

Manufacturing equipment

Agricultural machinery

General plant maintenance

Equipment repair

Its medium-strength characteristics make it a versatile option for threaded joints that need reliable vibration resistance while remaining serviceable.

Advantages of LOCTITE 243

Prevents Vibration Loosening

The cured adhesive locks the mating threads and helps prevent fasteners from loosening under vibration and dynamic loading.

Medium Strength

It provides a useful balance between locking performance and future disassembly.

Oil Tolerance

The formulation provides good tolerance to minor oil contamination, making it suitable for many maintenance environments.

Broad Metal Compatibility

It can be used on many common metal fasteners, including stainless steel and plated surfaces.

Easy Application

As a one-component liquid, LOCTITE 243 requires no mixing before use.

Helps Reduce Mechanical Locking Hardware

In suitable applications, threadlocking adhesive can reduce reliance on mechanical locking methods such as lock nuts, spring washers and similar devices.

LOCTITE 243 vs LOCTITE 271

Feature

LOCTITE 243

LOCTITE 271

Strength

Medium

High

Colour

Blue

Red

Typical purpose

General threadlocking

Permanent/high-strength threadlocking

Disassembly

Generally possible with hand tools

Typically requires greater removal force

Maintenance

Suitable for serviceable assemblies

Better suited to assemblies not routinely disassembled

The appropriate product should be selected according to fastener size, strength requirement, operating temperature, vibration, service conditions and desired disassembly characteristics.

Important Application Considerations

LOCTITE 243 is intended primarily for metal threaded assemblies. It should not be treated as a universal adhesive for bonding large surfaces or non-threaded components.

For critical applications, evaluate:

Fastener size and material

Thread clearance

Operating temperature

Vibration and mechanical loads

Chemical exposure

Surface cleanliness

Required disassembly torque

Cure time and service temperature

For passive metals or very low temperatures, curing may be slower and an appropriate activator may be required.

Product Summary

LOCTITE 243 is a blue, medium-strength anaerobic threadlocker designed to prevent loosening of threaded fasteners caused by vibration and shock. Its good oil tolerance, compatibility with a wide range of metal fasteners and ability to be disassembled with conventional tools make it a versatile solution for industrial assembly, automotive applications, machinery maintenance and mechanical repair.