What’s the Difference between Colors of Loctite Threadlockers? 


Loctite Threadlockers have revolutionized the way engineers address the issue of vibrational loosening in various applications, from automotive maintenance to household repairs. With a long history dating back fifty years, Loctite Threadlockers have provided a reliable and efficient solution to the problem. By offering a liquid adhesive that can lock and seal threaded fasteners, Loctite has eliminated the need for mechanical locking devices like split washers or nylon nuts, which come with their own set of issues such as loosening under vibration and lack of thread sealing.

Choosing the Right Loctite Threadlocker

Loctite Threadlockers are divided into four different colors, each representing a specific strength grade to suit different requirements. Understanding the differences between these colors is crucial in selecting the appropriate one for your specific needs. Let’s take a closer look at each color and its recommended usage:

Loctite Purple (222): Low Strength Threadlockers

Loctite Purple

Loctite Purple offers low strength and is ideal for fasteners with a diameter less than 6mm. It is suitable for all metal threading and works well with low strength metals such as aluminum that are prone to fracture. This grade allows for easy disassembly using hand tools and is commonly used for screws, including set screws. Loctite Purple is also effective for calibration screws, meters, and gauges. It typically takes around 24 hours to fully cure.

Loctite Blue (243): Medium Strength Threadlockers

Loctite Blue, a medium strength adhesive, is suitable for all metal threading and offers reliable performance. It is commonly used in machine tools, presses, pumps, compressors, and gear boxes. With a strength grade suitable for fasteners up to 20mm, Loctite Blue can handle minor contamination from industrial oils. Similar to Loctite Purple, it allows for disassembly using hand tools and takes approximately 24 hours to fully cure.

Loctite Blue

Loctite Red (262): High Strength Threadlockers

Loctite Red is a medium to high strength adhesive that fluoresces under UV lighting, making it ideal for quality control and monitoring purposes. It is suitable for all metal fasteners and can tolerate slight contamination from industrial oils. Loctite Red is perfect for applications requiring permanent assembly, such as heavy equipment, suspension bolts, motor and pump mounts, bearing cap bolts, and studs. It provides secure locking for threading up to 27mm and larger in diameter.

Loctite Red

Loctite Green (294): Penetrating Threadlockers

Loctite Green, the highest strength grade, is a dark green fluorescent adhesive that excels in capillary action and low viscosity. Unlike other grades, it works best between “engaged threads” and does not require disassembly before application. Loctite Green is effective with oil-coated fasteners and allows for removal using heat and hand tools. It is commonly used with preassembled fasteners, instrumentation screws, electrical connectors, and carburetors. This grade is suitable for threading up to 14mm.

Loctite Green

Additional Information

Loctite offers a variety of liquid adhesives and sticks as alternatives to threadlockers, ensuring flexibility in product selection. Regardless of the chosen type, all Loctite threadlockers deliver excellent locking and sealing performance, with a cure rate of 24 hours. Moreover, these threadlockers exhibit a wide temperature resistance range, spanning from -65 degrees Fahrenheit to 650 degrees Fahrenheit, depending on the adhesive grade.

In conclusion, Loctite Threadlockers provide a reliable solution for secure metal-to-metal applications. By understanding the variations in colors and their recommended uses, you can make an informed choice to ensure the success of your project.

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