Lava lamp
A lava lamp (or Astro lamp) is a novelty item used more for decoration than illumination—the slow, interesting rise and fall of variously-shaped blobs of wax is suggestive of lava, hence the name. The lamps are available with a variety of styles and colors of wax and liquid.
Glitter lamps with sparkly confetti (rather than wax) in the liquid have a similar motion to lava lamps but are not considered true lava lamps. They do have the advantage that they start up in under a minute rather than 30 minutes.
Operation
The lamp contains a standard incandescent bulb or halogen lamp which heats a tall (often tapered) glass bottle containing water (often with glycerol derived additive) and a transparent, translucent or opaque mix of wax and carbon tetrachloride (although other combinations may be used).[1] The wax is slightly denser than water at room temperature but is less dense under warmer conditions.[2] This occurs because wax expands more than water when both are heated.[3] When heated, the wax becomes fluid, its specific gravity decreases, and blobs of wax ascend to the top of the device[4] where they cool and then descend. 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 bulb is normally about 25 to 40 watts. It may take 20 to 60 minutes for the wax to warm up enough to freely form rising blobs (depending on the original temperature).
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. The only means to recombine the cloud of wax is to turn off the lamp and wait a few hours for the wax to settle back down at the bottom, forming one blob once again.
History
Singapore-born Englishman Edward Craven-Walker invented the lava lamp in 1963. His U.S. patent 3,387,396 for "Display Device" was filed in 1965 and issued in 1968.[5] 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 Hy Spector bought the U.S. rights and produced it as the Lava Lite via Lava Corporation or Lava Manufacturing Corporation; this was the first use of the word "lava" for this lamp. Wertheimer sold his shares to Hy Spector. Spector went on to manufacture and market the Lava Lite in his Chicago factory at 1650 W. Irving Park Rd in the mid-60s. 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 Eddie Sheldon and Larry Haggerty of Haggerty Enterprises. Haggerty Enterprises continues to produce and sell the Lava Lamp in the US, using the name of Lavaworld. "Lava lamp" has been used as a generic term but Lavaworld has claimed violation of trademarks.[6] 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.
Hazards
In 2004, Phillip Quinn, a 24-year-old of Kent, Washington, was killed during an attempt to heat up a lava lamp on his kitchen stove while closely observing it from only a few feet away. The heat from the stove built up pressure in the lamp until it exploded, spraying shards of glass with enough force to pierce his chest, with one shard piercing his heart and causing fatal injuries.[7] The circumstances of his death were later repeated and confirmed in a 2006 episode of the popular science television series MythBusters. The show also proved that even if shards of glass are not thrown with lethal velocity during such an attempt, the resulting spray of hot liquid from the lamp could easily cause severe burns to anyone nearby. The show also noted that the safety instructions clearly state that lava lamps should not be heated by any source other than the specially-designed bulbs and bases that are provided.[8]
See also
- Lavarand, random number generator that used lava lamps.
- Plasma globe
- Lava
Notes
- ^ U.S. patent 3,570,156 p 2 line 30
- ^ U.S. patent 3,570,156 p 1 line 40
- ^ U.S. patent 3,570,156 p 1 line 45
- ^ U.S. patent 3,570,156 p 1 line 47
- ^ Patent 3570156
- ^ Legal Threats from Lavaworld. - Oozing Goo Lava Line
- ^ Lava Lamp Death at Snopes.com.
- ^ Mythbusters, Season 4, Episode 60: Earthquake Machine, first aired August 30, 2006.
External links
- How Do Lava Lamps Work? (from The Straight Dope)
- How Liquid Motion Lamps Work (from howstuffworks.com)
- Basics of lava-lamp convection, by Balázs Gyüre and Imre M. Jánosi, Phys. Rev. E, 80, 046307 (2009).