Lava lamp

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(Redirected from Lava Lite)

A lava lamp is a novelty item typically used for decoration rather than illumination. The gentle flow of randomly-shaped blobs of wax suggests the flowing of lava. The lamps are available with a wide variety of container styles and colours of wax and liquid.

1 How it works
2 History
3 Hazards
4 See also
5 References
6 External links

The lamp consists of an illuminating bulb which heats up the lamp's contents, a glass bottle containing water and a translucent mix of wax and carbon tetrachloride (although other combinations may be used), and a metallic wire coil. The glass bottle sits on top of the bulb. The metallic wire coil is hidden in the base of the lamp, on which the glass bottle is sitting.

The wax is slightly denser than the water at room temperature, and slightly less dense than the water under marginally warmer conditions. This happens because the wax expands more than the water when both are heated.

While common wax is much less dense than water and would float in it at any temperature, a heavy, nonflammable solvent is added to tune the wax density to be just slightly higher than that of water.

When the lava lamp is turned on, the light bulb heats the bottom of the glass bottle which in turn heats the contents of the glass bottle in this vicinity.

Wax at the bottom heats until it melts, and eventually becomes less dense than the liquid above it. At this time, a portion of the wax rises towards the top of the container. Near the top, away from the heat source, the wax cools, contracts, and as its density increases it begins to fall through the liquid towards the bottom of the container again. Part of the reason for the shape of the lava lamp is that at the narrow tapered end there is more surface area per unit volume of liquid, therefore making liquid in this area experience a higher rate of cooling than that at the bottom, even if the lamp itself were off. This is a macroscopic, visible, form of convection heat transfer, although it also occurs on a molecular scale within the liquid itself. The difference in temperature between the top and bottom of the globe is only a few degrees.

One mass of wax may rise as another falls. The metal coil at the bottom helps to overcome the surface tension of the individual wax droplets, causing the descending blobs to coalesce into a single molten wax mass at the bottom of the container. The cycle of rising and falling wax droplets continues so long as the bottom of the container remains warm and the top of the container remains cool. Operating temperatures of lava lamps vary, but are normally around 60 °C (140 °F). If too low or too high a wattage bulb is used in the base, the "lava" ceases to circulate, either remaining quiescent at the bottom (too cold) or all rising to the top (too hot).

Chaotic behavior makes the movement of the wax unpredictable. The Lavarand system used this unpredictability as the basis of a hardware random number generator.

An Englishman, Edward Craven Walker, invented the original and best-known lava lamp in the 1960s. His U.S. Patent 3,570,156 for "Display Device" was filed in 1965 and issued in 1968.[1] Walker's company was named Crestworth and was based in Poole in the United Kingdom.

Walker named the lamp Astro and had various variations such as the Astro Mini, the Astro Coach lantern and presented it at a Brussels trade show in 1965, where the entrepreneur Adolph Wertheimer noticed it. Wertheimer and his business partner William Rubinstein bought the American rights to the product and began to produce it as the "Lava Lite"® via a corporation called Lava Simplex International, which is the origination of the use of the term "lava" in conjunction with this sort of lamp. Wertheimer dropped out of the development of the product, while Rubinstein went on to manufacture and market the "Lava Lite" in his Chicago factory in the mid-60's. The lamps were a huge success nationwide throughout the rest of the '60s and early '70s.

The lava lamp became an icon of the 1960s, where the constantly changing, brightly coloured display has been compared to the psychedelic hallucinations of certain popular recreational drugs. Lava Simplex International also produced the "Wave Machine", the "Gem Light", the "Timette Wall Clock" and the "Westminster Grandfather Clock".

In 1986, Mr. Rubinstein and his partner Hy Spector sold Lava Simplex International to Eddie Sheldon and Larry Haggerty of Haggerty Enterprises. Haggerty Enterprises continues to produce and sell the Lava Lamp product line in the US, using the name of Lavaworld. "Lava lamp" has been widely used as a generic term for this sort of lamp, but Lavaworld has claimed such usages to be a violation of its trademarks.[2] Lavaworld has since closed their production facilities in the USA and have outsourced their lamps to mainland China.

In the 1990s, Mr. 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 other related products. Mathmos lava lamps are still made in the original factory in Poole, Dorset where they were first made.

An episode of the TV show MythBusters demonstrated that heating a lava lamp on a stove could cause the lamp to explode, and injuries sustained from such an explosion could be fatal.^[1] The inspiration for that experiment came from a news story concerning a Kent, Washington, man who in 2004 died after a lava lamp that he was heating on a stove (in order to bypass the time delay associated with heating the wax) exploded, sending glass shards into his chest.^[2]