Threadlocker
A liquid adhesive applied to threaded fasteners to prevent them from loosening due to vibration or stress.
Threadlocker is a specialized anaerobic adhesive applied to the threads of fasteners, such as bolts and screws, to prevent them from loosening over time. Unlike standard adhesives that dry in the presence of air, anaerobic adhesives remain liquid until they are confined between close-fitting metal threads, where they polymerize into a tough, solid plastic. This cross-linked polymer fills all microscopic gaps between the threads, creating a mechanical lock that resists vibrations, shock, and thermal expansion.
Threadlockers are categorized by strength, typically color-coded for easy identification: purple (low strength for small fasteners that require frequent disassembly), blue (medium strength for general fasteners that can be removed with hand tools), and red (high strength for critical fasteners, such as cylinder head bolts or suspension links, requiring heat to disassemble). Applying the correct type of threadlocker is crucial for safety and ease of maintenance.
In addition to preventing loosening, threadlocker acts as a thread sealant, protecting the connection from rust and corrosion by blocking moisture and chemical entry. When applying threadlocker, it is essential to clean the threads of any oil, grease, or dirt to ensure proper adhesion. A small drop on the leading threads is usually sufficient to secure the fastener.