A lava lamp is an iconic decorative item and is relaxing to watch, as coloured blobs move around in a glass jar. If you purchase a lava lamp at a novelty store, you have plenty of choices when it comes to colour. While the type of wax used in a lava lamp is important, the bulb is the most vital piece of equipment for the lamp, because it must be warm enough to melt the wax without overheating it.
The wax needs to be lightweight enough to float when it gets warmed with the heat of the incandescent light bulb. Paraffin wax is most suitable. When it heats, it rises to top of the lava lamp, where it cools and begins to fall to the bottom once again. The movement of the lava lamp wax and the cohesive bubbles it forms in the glass is caused by the liquid mixture of water and oil. The wax takes longest to warm up--usually 20 to 30 minutes before it starts floating around.
Lava lamp fluid is comprised of different materials, though they are often water and oil. OozingGoo.com suggests mixing distilled water and pickling salt to use as the liquid base for a homemade lava lamp. Traditionally, mineral oil, distilled water, and isopropyl alcohol are mixed together slowly, which allows the heated wax to rise and form into floating blobs. The website also suggests adding antifreeze to a home mixture, which will allow the wax to heat faster.
Coloured wax is simply made by adding dye to the wax mixture before adding it to the lamp glass. The same goes for lamps with coloured liquid. Since the lamp contains distilled water, the dye or food colouring mixes with the water to create a contrast colour for the wax.