Review Content cool lamp for 70s vibe Cool retro feel with modern stainless steel trim Grandson likes Lava Lamp I purchased this Lave Lamp for my grandson. They are going to use it in their bedroom as a night-light. He loves the purple. BEAUTIFUL AND RELAXING TO WATCH Since the liquid is clear and the purple matter is dark, you can observe the motion of the lamp more clearly than if there were two colors. It cannot be left on continuously for more than 6-8 hours - it does heat up after that time quite a bit. It takes about 90 minutes to heat up, but once it does, I really enjoy watching it. LOVE the color!