How and When to use a Thread Locker

Hernon Threadlocker

Nuts N’ Bolts® 429 (applied above) is a single component anaerobic thread locking adhesive suitable for temperatures up to 300° F (149° C) and exposure to most solvents. Continue reading to see how and when to use a thread locker.

What is a thread locker?

Thread lockers are low viscosity adhesives applied to threaded assembles like nuts and bolts. The purpose is to lock the assembly in place after tightening to ensure no loosening or “backing out” occurs.

How to use a thread locker.

To use, apply a small amount of thread locker to the front threads of the bolt. As the bolt screws into the nut or retaining piece, the thread locker will coat the female threads. Apply only one drop for most applications. See the picture left for an example.

When to use a thread locker.

Thread lockers are recommended for use any time a threaded faster will be exposed to vibration or repeated impacts. Even when vibration is not a factor, thread lockers are advised when a threaded assembly is critical to a product’s structure and function.

Which thread locker should I use?

Thread lockers are available in a variety of strengths, colors, and grades. However, there are four main types based on the strength of the desired bond and wicking properties: Low, Medium, High and Wicking. As you may have guessed, “Low” provides low strength bonds that can be disassembled using hand tools. Use low strength when you want some extra assurance that a fastener will hold but you know it will need to be disassembled routinely. Regarding medium strength, users can disassemble threaded assemblies bonded with medium strenth thread lockers using power tools. Use Medium strength thread lockers for critical joints that may only rarely need disassembly. High strength thread lockers are for permanent bonds. Disassembly will only be possible through a combination of high heat and power tools.

Never use high strength thread lockers on a threaded assembly that is likely to need disassembly during the lifetime of the product. Using high heat to disassemble fasteners bonded with high strength thread locker may warp or damage nearby components. Finally, Wicking grades are unique in that they can wick into place on already assembled fasteners. Use wicking thread lockers to retrofit thread lockers into already assembled fasteners or to address specific challenges in the manufacturing process.

Thread lockers seal leaks and resist loosening.

Active thread lockers by Hernon Manufacturing cure quickly at room temperature under anaerobic conditions. These adhesives assist threaded assemblies by improving their holding power and reliability. Thread lockers improve reliability by resisting the loosening of threaded fasteners due to vibration and impacts. They also seal threads against leaks and contamination from outside materials. Thread lockers will naturally prevent corrosion by keeping fluids out of the threads and providing a barrier against galvanic corrosion.

View Hernon Manufacturing Threadlockers


  • Nuts N’ Bolts® 423: A single component anaerobic thread locking material, which is thixotropic and develops medium strength.
  • Nuts N’ Bolts® 427: A single component anaerobic thread locking material, which develops high strength.
  • Nuts N’ Bolts® 432: A single component anaerobic threadlocking compound designed for heavy duty applications subject to operating temperatures to 450ºF (232ºC).
  • Nuts N’ Bolts® 434: A thixotropic, 100% active anaerobic compound which solidifies with reliable and expected strength upon application to most fasteners.
  • Nuts N’ Bolts® 439: A single component, high strength anaerobic adhesive. Nuts N’ Bolts® 439 cures when confined in the absence of air between close fitting metal surfaces and prevents loosening and leakage from shock and vibration.



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