Red Loctite threadlocker is considered to have high adhesion strength. It cannot be removed by simply applying torque but requires special heat in combination with torque (or special chemicals) to disassemble the components after the red Loctite threadlocker has been applied.
Green Loctite threadlocker is considered to have high adhesion strength for wicking. It is ideal for preassembled fasteners, like set screws. It cannot be removed by simply applying torque but requires special heat in combination with torque (or special chemicals) to disassemble the components after the green Loctite threadlocker has been applied.
Blue Loctite threadlocker is considered to have medium adhesion strength. It can be disassembled with high torque, but it is easier to disassemble with special chemicals and/or heat. It is available as a tape, semisolid, or liquid form, and once applied to the threads it will cure in 24 hours.
Purple Loctite threadlocker is considered to have low adhesion strength. It can be disassembled with low torque with the same hand tool used to install it.
Metric Layover Sizing Chart
Click On Image for PDF. Print Full Scale to Match Fasteners by Shape and Size