Fig. 6 and Fig. 7 display the measured temperature evolution at circle B of the reheated preform as a function of reheating time using the transparent far infrared tungsten lamp and the far infrared quartz lamp, respectively. The results are shown for three different locations through the thickness of the preform under three voltage settings of lamps, as shown in Table 1. It can be seen that the voltage or the temperature of heating lamps has a strong effect on the heat up rate of the preform. Increasing the heating lamp temperature leads to a faster heat up rate, whereas the lamp temperature has little effect on the temperature difference through the wall of the preform at the end of reheating. The heat up rate decreases with increase of the distance from the external surface of the preform. A comparison between Fig. 6 and Fig. 7 shows that the transparent far infrared tungsten lamp leads to a higher heat up rate than the far infrared quartz lamp. Shown in Fig. 8 is the reheating time required for heating the location at a distance of 2 mm to a temperature of 110 °C. It can be seen that the reheating time required for the infrared quartz lamp is nearly twice as large as that for the transparent far infrared tungsten lamp.