History of Lava Lamps
Lava Lamps (or Lava Lites) have been around longer than anyone can really
remember. A man named Craven Walker saw a similar type lamp in a pub where he was
drinking an ale. He described it as a "contraption made out of a cocktail shaker,
old tins and things."
Walker, being an inventor, was determined to make an even better version of the
lamp and spent the next 10 years working on a better model (during this time he
also ran a house-swap agency and made a film on nudism). Once Walker perfected the
right combination of oil, wax, and other solids, he named the new lamp Astro. The
original version had tiny lights at the bottom to simulate starlight. He made several
different versions of it – the Astro Mini and the Astrao Coach lantern were two
such versions. In 1964, he took the light to a trade show in Brussels to show it
off.
At the trade show, a man named Adolph Wertheimer noticed the Astro lamp and thought
it was really cool. He and his partner, Hy Spector, paid Walker for rights to sell
the lamp in the United States. They built the lamps in Chicago (where they are still
built today) and named the new lamp Lava Lite. A legend was born.
How a lava lamp works
How a lava lamp works is a bit of a secret but of course, Reeko knows no secrets
when it comes to science. The lamp consists of an incandescent bulb which heats
the contents of a tapered glass bottle containing water and a clear mix of wax and
carbon tetrachloride. A metal wire coil at the base of the lamp enhances the heat
convection.
The wax is just slightly denser than the water and will
float when the lamp is turned off. By adding a nonflammable solvent to the
wax, the density is adjusted so it is very close to the density of the water. The
wax is slightly denser than the water at room temperature (and will sink) and slightly
less dense than the water under marginally warmer conditions (so it will float).
The density is so close to that of water, that the floating effect occurs as the
was reaches the bottom of the lamp and is heated by the light bulb. When the wax
reaches the top and is further away from the lamp, it slowly cools and sinks back
to the bottom. The temperature difference between the top of the lamp and the bottom
only differs by a few degrees.
The lava lamp owes its classic shape to physics as much as aesthetics: at the tapered
end there is more surface area per unit volume of liquid, hence the liquid in that
area undergoes a higher rate of cooling than the liquid nearer the bottom. The whole
process is a macroscopic, visible, form of convection heat transfer, although it
also occurs on a molecular scale within the liquids themselves.