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      • Published 11 Jan 2023
      • Last Modified 29 Aug 2023
    • 7 min

    A Complete Guide to Thread Lock

    Our guide explains all the different types, strengths, and exactly what thread lock is used for.

    What is Thread Lock?

    Thread lock is a type of anaerobic adhesive used to protect, strengthen, and seal various types of threaded fasteners. Suitable for use in a wide range of applications and environments, thread lock can be used with delicate components and heavy-duty industrial assemblies alike.

    Thread locking adhesive is used for a range of different purposes, from tamper-proofing equipment to safeguarding against movement or unwanted loosening of components. It provides a handy, reliable solution thanks to its quick drying time, ease of application, and simple way of working.

    There are many benefits and advantages to using thread lock, including:

    • Versatility and adaptability
    • Suitability for use with a wide range of materials and components
    • Protects against corrosion
    • Ease of application
    • Lubricates threads
    • Provides a high level of chemical resistance

    Thread Lock Strengths

    Thread lock is typically available in three different strengths – low, medium, and high. Each has unique benefits and best-suited applications, so the best strength thread lock will ultimately depend on your specific project requirements.

    Low Strength

    • Best suited to use with small parts
    • Straightforward to remove

    Medium Strength

    • Can be used with larger components
    • Designed to be removed with hand tools

    High Strength

    • Suitable for use with the largest fasteners
    • Localised heat will be required for removal

    Thread Lock Colours

    Thread lock can also be categorised by colour. In the majority of cases, the different colours typically refer to the different grades of thread locker. In essence, think of it as a handy colour code designed to help you distinguish between the different types. While not all manufacturers use this colour code, many leading brands such as Loctite do. Therefore, it is important to ensure you are aware of the meaning behind each colour.

    Purple Thread Lock

    Purple thread lock is typically low strength and medium viscosity. It is a popular option thanks to the flexibility it allows, enabling easy disassembly when required.

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    Blue Thread Lock

    Blue thread locker is medium strength and medium viscosity. Although blue thread locker strength is relatively high, this type of fastening is not permanent, and it can be removed using hand tools.

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    Red Thread Lock

    Red thread lock is a high strength adhesive. It is the most permanent type and requires the application of localised heat to loosen.

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    Green Thread Lock

    Green thread lock is high strength and low viscosity. It can be used for wicking and is designed to provide a durable, long-lasting fastening solution.

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    Applications and Uses

    Thread locker uses are varied and can encompass a wide range of applications and environments. However, in simple terms, thread lock is primarily used to prevent unwanted loosening of fasteners.

    Some of the most notable thread lock applications include:

    • Securing components and assemblies
    • Protecting against loosening via vibration or thermal expansion
    • Acting as a sealant to protect against potential leaks
    • Providing a certain level of corrosion resistance
    • Acting as a thread lubricant
    • Keeping assemblies in good working order

    Additional uses for thread lock are explained below.


    Although gasketing is often referred to under the same terms as thread lock, the two are different fastening solutions. While thread lock typically secures fasteners, gasketing is more of a form in place sealing gasket than a standard thread retainer.

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    Retaining thread locker is designed to prevent loosening by vibration. It can also protect against unintentional loosening by personnel. Typical applications include bonding fitting cylindrical components.

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    Structural Bonding

    Structural adhesive thread lock is tough and durable, providing strong adhesion to a range of different or dissimilar materials. It typically features a high shear strength and is resistant to tampering, impact, and fatigue.

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    Tamper Proofing

    Thread lock can be used to safeguard against unwanted tampering by providing an effective sealant protecting components and assemblies. It is designed to allow any changes or movement to be spotted easily. Depending on the setting and requirements, certain types of epoxy coatings may also prove useful when it comes to tamper-proofing.

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    Types of Thread Locker

    There are various forms of thread locker, each best suited to different applications and environments. The different types of thread locker are available in a range of strengths, including low-strength, medium-strength, and high-strength adhesive. However, it should be noted that even high-strength threadlocking types are not permanent and all forms of thread locker can be removed with the application of heat, tools, and varying levels of effort.

    Some of the key types of thread lock are detailed below.

    Thread Locking Liquids

    Liquid is the most common type, largely because thread locking fluid is easy to dispense, apply, and store.

    Liquid thread lock is ideal for everyday use with standard assemblies, yet it can also be used with trickier components such as blind holes and fine threads.

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    Thread Locking Paste

    Thread locking paste is typically quick-drying and easy to apply to a range of materials including metals.

    Its advantages over liquid thread lock include non-drip properties and the fact that it becomes brittle once it is fully cured. This means that it is much easier to see any movement of the parts or potential tampering that may have occurred.

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    Thread Locking Wax

    Thread locking wax is typically found in a tube for easy application, similar in appearance to a standard glue stick.

    Wax is beneficial as it prevents accidental spillage, while the stick format allows for easy application and more precise manoeuvrability.

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    What Materials Can Be Used with Thread Lock?

    Thread lock can be used on a wide array of different materials, including plastics, composites, and metals. Some types of thread lock are best suited for use with specific materials, so be sure to double-check before use. It is also worth noting that you may find it advantageous to use a specialist primer before applying thread lock with certain materials such as inactive metals (plated or oxidised metals, for example).

    Top Tip!

    Before applying thread lock, make sure that the component or assembly and the area immediately surrounding it is clear and thoroughly cleaned. You will also need to ensure that it is free from debris and any potential contaminants such as oil, dust, or grease. This will help to achieve a smooth finish and ensure the thread locking can perform optimally.

    How Long Does Thread Lock Take to Cure?

    Various factors dictate the length of time that thread lock takes to cure, and you should always take care to familiarise yourself with the manufacturer’s guidelines before use as cure time will vary between different thread locking products.

    Other considerations you should bear in mind include:

    • The material where the thread lock will be applied
    • Environmental factors such as temperature
    • The size of the part or component and the amount of adhesive required

    However, with that in mind, most standard types of thread lock have a curing time of 24 hours. Some quick-drying varieties take only 1-3 hours to cure, while others can take up to 72 hours for full curing.

    How Do You Remove a Fastener Once Thread Lock is Cured?

    Thread lock is not a permanent solution, but the ease of removal will depend on the strength of the particular adhesive in question. Low and medium-strength thread lock should be fairly straightforward to remove with the application of standard hand tools. However, higher-strength thread lock will likely need the use of localised heat as well as hand tools to be successfully removed.

    Once the adhesive has been removed, you should be able to easily access the fastener or component as usual. Thread lock is a popular option thanks to the ease of disassembly it offers, especially when compared to alternative types of adhesive.

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