Thread lock keeps screws tight in high vibration applications. Thread lock goes on the threads of a screw before it's threaded into a nut or threaded socket. If you're trying to remove a screw and it seems like it's stuck for good, it probably has thread lock on it. Thread lock is kind of like rubber cement and doesn't hold up well under heat. Heat softens the thread lock enough to remove the screw. Thread lock is most commonly used on screws used to assemble radio-controlled vehicles.
Turn on the gas valve of a self-igniting propane torch. Pull the strike button to spark the gas into flame.
Hold the propane torch so that the flame heats up the threads of the screw. The heat will soften the thread lock.
Remove the screw from the nut or threaded socket with a screwdriver.
Scrape the thread lock off the threads with an ice pick. If the screw has already been removed and you're just trying to clean the threads, hold the head of the screw in the jaws of a pair of pliers to make cleaning easier. Wipe the softened thread lock off the threads with a paper towel.
Heat the thread lock as many times as necessary to remove it.
Follow all safety instructions on the label of the self-igniting propane torch. Don't touch the threads of the screw after heating or you'll get burnt.