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What is “blue” Loctite?

Blue Loctite is the name used for a medium strength thread locker manufactured by Henkel Loctite. The most common “blue” Loctite is Loctite 243. Other versions include Loctite 242, 248, 2432 and more.

Blue Loctite is used to seal and lock metal fasteners. It works on all metals, preventing loosening from shock and vibration. Blue Loctite prevents fluids to leak out or in due to gaps in threads. Its action protects components from rusting and corrosion. It can be applied quickly and cures in about twenty-four hours.

Blue thread lockers are available in tape, semisolid, or liquid form. Loctite 248, for instance, comes as paste in a stick dispenser. Loctite 249 is an acrylic film tape, useful where a liquid product may be difficult to apply.

What is blue Loctite used for?

Blue Loctite is a general purpose thread locker. It is commonly used on fasteners up to 20 mm size. Blue Loctite is designed to be removed with hand tools. This means it’s ideal for parts that need occasional servicing, including car parts, motorised yard equipment, bicycles, furniture and more.

Different versions of blue Loctite can have distinct properties and specific applications. Loctite 243 is more resistant to oil, compared to Loctite 242. Loctite 2432 is a nuclear grade fluid: it was developed for use on sensitive metals, like titanium, used in the nuclear industry.

Common tools will usually be enough to disassemble parts treated with blue Loctite. If the fasteners are stuck, heat can be applied to make removal easier. A simple propane or butane torch will serve the purpose.

What is the difference between blue Loctite and other thread lockers?

Loctite thread lockers are colour-coded to indicate strength. The coding is based on U.S. military specifications. It has been adopted by most thread locking fluid manufacturers.

There are four basic colours: purple, blue, green and red.

  • Purple: Low strength. Used on small parts that require regular adjustment. Easily removable. Great for soft metal like aluminium and brass.
  • Blue: Medium strength. General purpose. Used on components that may need disassembling in the future.
  • Green: High strength. It is thin and flows in tight, difficult to reach cracks and crevices. Recommended for preassembled fasteners, instrumentation screws and electrical connectors. There is no need to disassemble parts before application.
  • Red: High strength. Ideal for high vibration applications. Very strong bonding, will require heat for removal. Recommended for permanent assembly.

Our Loctite products

Conro Electronics, as an electronic manufacturing and adhesives distributor, offers a wide choice of Loctite thread lockers, including “blue” Loctite 243.

We’ll show you how to improve product reliability while increasing performance and lowering costs. Our team of technical support specialists will provide your company with dependable global supply, unrivalled efficiency, and superior technical support.

Feel free to contact us on 0208 953 1211 or send us an email to

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