Lava lamp

Background

A lava lamp is a decorative tube-shaped light fixture containing a colored, oily fluid that flows up and down throughout the lamp chamber in a manner reminiscent of molten lava. As the fluid rises and sinks in the lamp chamber it changes shape and breaks into globules of various sizes, giving a psychedelic effect of constantly shifting patterns. Credit for the creation of the lava lamp is given to English engineer Craven Walker who, in the late 1940s, saw a prototype of the lamp in a pub in Hampshire, England. This early version, according to the Walker legend, was made of "a cocktail shaker, old tins and things." He purchased the liquid-filled fixture and set out to make his own. Walker formed the Crestworth Company in Dorset, England, and over the next 15 years tried to build a better lava lamp. When first marketed under the name Astro Lite in British stores in the early 1960s, it was not an immediate success. Then, at a 1965 German trade show, two American entrepreneurs saw an early model on display, and bought the rights to manufacturer the lamp in North America. In the United States, they changed the name from Astro Lite, to the infinitely hipper Lava Lite Lamp and began manufacturing operations in Chicago. With the advent of psychedelia and pop-art later that decade, Walker's gimmicky contraption became a major fad. By the time Walker left the business in 1990, he had sold over seven million of his creations. Today, the company ships 400,000 lamps a year to shops around the world. Currently, Haggerty Enterprises is the only U.S. manufacturer of Lava Lite Lamps and they distribute them nationally through a number of retail and mail order outlets.

Design

The lava effect is due to the interaction between the fluids used in the lamp. These fluids are selected on the basis of their density so one tends to barely float in the other. In addition, they are chosen based on their coefficient of expansion, so as they are heated one tends to rise or sink faster than the other. When heat from the light bulb warms the heavier liquid sitting on the bottom, it gets hotter and, due to its lower density, rises to the surface. By the time the "lava" reaches the top of the lamp, it begins to cool, becomes denser, and sinks to the bottom. As the lava sinks, it gets closer to the light bulb, heats up again, and the process is repeated over and over. Therefore, the key to successful lava lamp design is the selection of appropriate immiscible fluids. The exact composition used in lava lamps is a proprietary secret, but in general terms, one fluid is water based and the other is oil based. The aqueous phase may be water mixed with alcohol or other water-soluble solvents. The second fluid must meet a number of design criteria: it must be insoluble in water, heavier and more viscous, non-reactive and non-flammable, and reasonably priced. It must also be non poisonous, unchlorinated, not emulsifiable in water, and must have a greater coefficient of expansion than water.

While fluid selection does not change from lamp to lamp, there are design changes to be considered because lamps are available in different colors, sizes, and styles. The original Century model, which is still manufactured today, was the most popular model during the 1960s and 1970s. Its gold base is perforated with tiny holes which simulate starlight and its 52 oz (1.46 kg) globe is filled with red or white lava and yellow or blue liquid. A number of interesting variations on the Century have been manufactured in past years, although not all of them are still made today. For example, the Enchantress Planter Lava Lite lamp came equipped with plastic foliage. The Continental Lava Lite lamp which, was the only cordless, non-electric model, featured a candle to warm the lava. The Consort Lava Lite lamp, according to the company's 1970s catalog, was designed with a more masculine look "perfect for the study or den, so right for the executive suite." There was also the Mediterranean Lava Lite lamp, which was decorated with black wrought iron. In addition, Haggerty offers so-called giant lamps, which range in size up to 27 in (68.6 cm) tall.

Raw Materials

As noted above, the actual ingredients used in Lava Lite Lamps are proprietary but there are several liquid ingredients, which can be combined to give a lava effect.

Liquid components

Lava-type lamps can be made with water mixed with isopropyl alcohol as one phase and mineral oil as the other. Other materials, which may be used as oil phase ingredients include benzyl alcohol, cinnamyl alcohol, diethyl phthalate, and ethyl salicylate.

Other additives

Other additives used in lava lamp fluids include various oil and water-soluble colorants. The specific gravity of the aqueous phase can be adjusted through the addition of sodium chloride or similar materials. In addition, a hydrophobic solvent may be added to the mixture to help the lava coalesce. Turpentine and similar paint solvents are said to work well in this regard. Antifreeze ingredients can also be added to increase the rate at which the lava warms.

Container

A clear glass cylinder is used to house the fluids and forms the body of the lamp. The classic lava lamp shape is an hourglass about 10 in (25.4 cm) high.

Heat source

A regular incandescent bulb is used as the source for both light and heat in a lava lamp. The type of light bulb is critical to ensure the lava is not over or under heated. Haggerty Enterprises lists several bulb types that are appropriate for their appliances, depending on which the model: 40 watt frosted bulb, 100 watt reflector bulb with inside frost, 7.5 watt bulb 40 watt candelabra type. Although it does not generate at much heat, a florescent bulb is used in their Pacifica model.

Hardware

Other items used in lava lamp production include the base plate, which houses the electrical components, 16-gauge lamp wire, and an electrical plug. Quarter inch (0.635 cm) thick foam rubber may be used as a gasket material to seal the chamber. Miscellaneous hardware, such as screws, is also used. Optional equipment, such as a light dimmer switch or a small fan, may be used for temperature control.

The Manufacturing
Process

The manufacturing process of the lamp consists of several steps, both automated and manual. According to a representative of Haggerty Enterprises, the company has the capacity to produce up to 10,000 lamps per day on their assembly line.

Container assembly

• The glass cylinder is fastened to the ceramic lamp fixture, which forms the base. The lamp is attached to the appropriate wiring and the bulb is screwed into place. The gaskets are glued into place to prohibit leakage. The containers are assembled and checked to make sure they are leak proof.

Compounding liquid phase

• The liquid phases are mixed and added separately. Isopropyl alcohol is used to lower the specific gravity of the water phase so the mineral oil floats appropriately. By mixing water and alcohol in the correct proportions, the mineral oil can be made to float. In 90% alcohol, the mineral oil will sink to the bottom. The addition of 70% alcohol will make the oil seem lighter until it is about to "jump" off the bottom. The correct ratio is about six parts 90% isopropyl alcohol to 13 parts of 70% isopropyl alcohol. Dyes, salt, etc. are then mixed into the water phase, and the oils and waxes are added to the second liquid. Some heating may be required to melt the waxy materials.

FiIling

• The lamps are moved along a conveyor line and first filled with the oil/wax phase, then the water phase. A small air-space of about 1 in (2.54 cm) is left at the top to allow for expansion of the hot liquids. This important because the amount of airspace can influence the size of the bubbles formed by the lava. After filling, the cylinder is capped with either a screw type cap or a bottle cap type, which is crimped into place.

Qucality Control

During the batching and filling processes, the liquids are checked to ensure they were correctly manufactured. The proper ratio and composition of the two liquid phases is critical to ensure that the lava effect will be achieved. An incorrect ratio may allow the oil and water phase to mix together, separate into bubbles which are too small, rise and fall as one continuous mass, or become mixed with the water and not separate at all. It is critical that all electrical connections are good and seals are tight to ensure safety and that there are no leaks. Improper gasket alignment or poor seals can result in leakage of the fluids. After filling, each lamp is checked to ensure the light bulb is completely centered and tightened. The bulb and socket may move slightly during shipping. If so, the owner is instructed to gently push the socket back to the center of base. Instructions on how to change the bulb are provided inside the lamp socket base. Variation in lamp size or wattage may yield unsatisfactory lava flow and may increase the risk of fire.

During initial use, the lava may not flow properly or may float to the top of the globe. If this happens, the lamp should be allowed to heat up for four hours or more to allow the lava material to become completely molten. Excessive agitation of the lamp may cause the fluids to intermingle and become cloudy, or may even result in permanent malfunction. The lamp should not be stored in direct sunlight as this may cause the colors to fade.

The Future

Given the proprietary nature of lava lamps, it is difficult to speculate on future improvements in the manufacturing process. However, it is interesting to note that computer technology has spawned its own version of the lava lamp—the virtual lava lamp. Also known as the Javalamp after the popular computer language, this virtual lamp is a computer animation that mimics the appearance of the real item.

Where to Learn More

Books

Popular Electronics Hobbyists Handbook. Germsback Publications Inc, 1992.

Other

Haggerty Enterprises Inc. Chicago, IL.

[Article by: Randy Schueller]

An original Mathmos Astro 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 they rely on convection rather than density changes and are not considered true lava lamps. They do have the advantage that they start up in under a minute rather than 30 minutes.

Contents 1 Operation 2 History 3 Hazards 4 See also 5 Notes 6 External links

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 the 1960s. 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, 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 Hy Spector bought the American rights and produced it as the Lava Lite via Lava Corporation or Lava Manufacturing Corporation, the origin 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 have 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

1. ^ U.S. Patent 3,570,156 p 2 line 30
2. ^ U.S. Patent 3,570,156 p 1 line 40
3. ^ U.S. Patent 3,570,156 p 1 line 45
4. ^ U.S. Patent 3,570,156 p 1 line 47
5. ^ Patent 3570156
6. ^ Legal Threats from Lavaworld. - Oozing Goo Lava Line
7. ^ Lava Lamp Death at Snopes.com.
8. ^ 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).

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