Threadlocker Adhesives

By SRT-Tom · Apr 16, 2021 ·
  1. SRT-Tom
    Threadlockers, as the name suggests, are used to lock the threads of fasteners such as screws, bolts, studs of different sizes which are used in different applications- especially automotive. This type of adhesive prevents loosening caused by vibration, mechanical and thermal shock.


    Chemically speaking, most thread-locking formulas are methacrylate-based and rely on the electro-chemical activity of a metal substrate to cause polymerization of the fluid. Thread-locking fluid has unique properties. It becomes fluid when shaken or stirred and returns to a gel state when allowed to stand. It flows in the presence of air, but when you spread it onto the threads of a fastener and tighten down, oxygen can't get to it. The threadlocker then polymerizes and effectively keeps the fastener from turning.

    Threadlockers have a broad temperature resistance of -65°F to 300°F, some going up to as high as 650°F . They can be permanent or removable; in the latter case, it can be removed with heat, for example. Typically, brands are color-coded to indicate strength and whether they can be removed easily or if they require heat for removal.

    Types of Threadlockers

    Red- Highest Full strength, permanent fix. Intended for fasteners that normally aren't removed without the application of high heat (i.e., a blowtorch) and a large amount of torque.

    Blue- The most commonly used. A medium-strength product. Can be disassembled with hand tools. To remove the fastener, simply unthread it. You'll feel a fair amount of initial resistance, and then the pieces will come apart easily. Clean and reapply every time the parts are assembled.

    Green- Recommended for locking preassembled fasteners (e.g., electrical connectors and set screws). The product is categorized as medium-to-high-strength for wicking. It is also available in a liquid form. It can be removed with heat and hand tools.

    Purple- Used on low-strength metals such as aluminum and brass. It can be removed with heat and hand tools.

    Forms and Manufacturers

    Threadlockers come in dropper bottles, lipstick-like tubes and gel-dispensing tubes. There are many manufacturers of this useful product. Here is a list:

    J-B Weld
    Gorilla Pro

    Application of Threadlockers

    Start with a clean set of threads, both male and female. Use mineral spirits, or carb or brake cleaner. There is also an aerosol spray cleaner/primer that will shorten the setting time, as well as clean the threads.

    Apply a few drops of threadlocker on the bolt, where the nut engagement area will be. No need to apply the threadlocker all the way around the bolt. As you twist on the nut, the product will spread around the bolt forming the seal.


    Don't touch the bolt to the dispensing nipple on the container or you'll transfer metal ions to the plastic. That contamination will eventually render the entire vial of threadlocker useless.

    Allow 24 hours to cure.

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