The standard deviation of the signals recorded from thermoluminescent LiF as a function of the thermal treatment before irradiation (pre-annealing) has been investigated (see preceding abstr). For pre-annealing temperatures higher than -50 degrees C, the standard deviation increases with pre-annealing temperature and time. A consequence is that in pre-annealing, high temperatures should be used for periods as short as possible. If the thermal treatment during the readout (a few seconds at approximately 300 degrees C) is the only high temperature treatment of the dosimeter between repeated irradiations, a standard deviation of 0.22% in the measured signals can be obtained. Different factors contributing to the standard deviation are analysed and, in consequence, a sensitive method for quantitative comparison between different readout instruments is given.