Heating cases can reverse work-hardening completely and make brass flexible and able to reform. This process of heating softens the brass and is called annealing.
During annealing the accumulated stress in the micro structure of the brass is cancelled and the brass brought back to its natural condition.
Apply a small dot of Tempilaq to the case body, plus minus 10mm below the shoulder. It has been proven that if the body reaches 475 degrees Fahrenheit 10mm below the shoulder, the neck has reached the required temperature of 650 to 700 degrees Fahrenheit.
Heat a Tempilaq marked case with the pencil flame pointing at the middle of the neck. The case is rotated by the drill at a moderate pace until the Tempilaq has melted. That is when the Tempilaq turns transparent from the normal white colour. When this happens, throw the case into cold water.
Since we want the Tempilaq to indicate the temperature of the brass, it means that the flame should NOT make direct contact with the Tempilaq.