Lava Lamps

A lava lamp (or Astro lamp) is a decorative novelty item that contains blobs of colored wax inside a glass vessel filled with clear liquid; the wax rises and falls as its density changes due to heating from a incandescent light bulb underneath the vessel. The appearance of the wax is suggestive of pāhoehoe lava, hence the name. The lamps are available in a variety of styles and coluors of wax and liquid.

Operation

The lamp contains a standard incandescent bulb or halogen lamp which heats a tall (often tapered) glass bottle containing oil (often with a glycerol derived additive) and a transparent, translucent or opaque mix of wax and carbon tetrachloride (although other combinations may be used). The density of common wax is much lower than that of water and would float on top under any temperature. However, the carbon tetrachloride is heavier than water (also nonflammable and miscible with wax), and is added to the wax to make its density at room temperature just little higher than that of the water. When heated, the wax mixture becomes less dense than the water because wax expands more than water when both are heated. It also becomes fluid, and blobs of wax ascend to the top of the device where they cool (which increases their density relative to that of the water's) and then descend.^[3] A metallic wire coil in the base of the bottle acts as a surface tension breaker to recombine the cooled blobs of wax after they descend.

The underlying mechanism is a form of Rayleigh–Taylor instability.

The bulb is normally about 25 to 40 watts. It may take 45 to 60 minutes for the wax to warm up enough to freely form rising blobs (depending on the original temperature). It may take 2 to 3 hours if it has been in a cold room for a long time.

Once the wax is molten the lamp should not be shaken or knocked over or the two fluids may emulsify and the wax/blobs will remain cloudy rather than clear. Some recombination will occur as part of the normal cycle of the lava in the container but the only means to recombine all of wax is to turn off the lamp and wait a few hours. The wax will settle back down at the bottom, forming one blob once again. Severe cases can require many heat-cool cycles to clear.

Briton Edward Craven-Walker invented the lava lamp in 1960. His U.S. Patent 3,387,396 for "Display Device" was filed in 1965 and issued in 1968. Craven-Walker's company was named Crestworth and was based in Poole, Dorset, in the United Kingdom. Craven-Walker named the lamp Astro and had variations such as the Astro Mini and the Astro Coach lantern. Craven-Walker presented it at a Brussels trade show in 1965, where the entrepreneur Adolph Wertheimer noticed it. Wertheimer and his business partner William M. Rubinstein bought the U.S. rights to manufacture and sell it as the Lava Lite via Lava Corporation or Lava Manufacturing Corporation. Wertheimer sold his shares to Hy Spector who took the product into production, manufacturing and marketing the Lava Lite in his Chicago factory at 1650 W. Irving Park Rd in the mid-60s. Rubinstein stayed on as a vice president. The lamps were a success throughout the 1960s and early 70s. Lava Corporation's name changed to Lava-Simplex-Scribe International in the early 1970s, and made instant-loading camera-film cartridges, as well as postage-stamp vending machines.

In the late seventies Spector sold Lava Simplex International to Micheal Eddie and Larry Haggerty of Haggerty Enterprises. Haggerty Enterprises continues to produce and sell the Lava Lamp in the US, using the name of Lavaglass. "Lava lamp" has been used as a generic term but Lavaworld has claimed violation of trademarks.^[5] Lavaworld has closed production in the USA and has outsourced their lamps to China.

In the 1990s, Craven-Walker, who had the rights to England and Western Europe, sold his rights to Cressida Granger, whose company, Mathmos, continues to make Lava Lamps and related products. Mathmos lamps are still made in the original factory in Poole. Mathmos is the only company worldwide to produce the lamp using the original formula, and the sole original manufacturers of the lava lamp

This is a temperature guide where it tells you if your lava lamp is working properly or you may need to  get a brighter/dimmer bulb according to what it is currently.