Some brands of lava lamps require up to six hours for the lava-like blobs to form and flow properly. Even with the long warm-up time, there is a limit to how long the lamp should be operated continuously to keep it functioning as designed. Do not run the lamp for more than eight to 10 hours straight.
Lava Lamp Use
While it may be tempting to operate your lava lamp all hours of the day and night, this can cause it to overheat, which may make the colored blobs stop moving in an amoeba-like fashion. If the lamp overheats, the colored liquid may form one large blob that seems to float without transforming into other shapes. Turn off the lamp and allow it to cool down before turning it back on. Once it cools, it should function properly again. A lava lamp may overheat in eight to 10 hours, depending upon the bulb and brand of lamp. Use the lamp for less than eight hours at a time for best results, allowing it to cool to room temperature before using it again.