As the lava sinks, it gets closer to the light bulb, heats up again, and the process is repeated over and over. By the time the "lava" reaches the top of the lamp, it begins to cool, becomes denser, and sinks to the bottom. 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.
![classic lava lamp yellow liquid red wax classic lava lamp yellow liquid red wax](https://i.ebayimg.com/images/g/NrYAAOSw-mNfao7M/s-l400.jpg)
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. These fluids are selected on the basis of their density so one tends to barely float in the other. The lava effect is due to the interaction between the fluids used in the lamp. manufacturer of Lava Lite Lamps and they distribute them nationally through a number of retail and mail order outlets. Currently, Haggerty Enterprises is the only U.S. Today, the company ships 400,000 lamps a year to shops around the world. By the time Walker left the business in 1990, he had sold over seven million of his creations. With the advent of psychedelia and pop-art later that decade, Walker's gimmicky contraption became a major fad. In the United States, they changed the name from Astro Lite, to the infinitely hipper Lava Lite Lamp and began manufacturing operations in Chicago. 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.
![classic lava lamp yellow liquid red wax classic lava lamp yellow liquid red wax](https://i.ebayimg.com/images/g/KQQAAOSwcm5fOGNh/s-l640.jpg)
When first marketed under the name Astro Lite in British stores in the early 1960s, it was not an immediate success. Walker formed the Crestworth Company in Dorset, England, and over the next 15 years tried to build a better lava lamp. 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. 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. 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. 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.