If you think back to the 60’s and 70’s your memories are probably illuminated by a lamp filled with swirling globs of colourful goop that really didn’t shed much light at all.
Lava lamps were invented in 1963 by a British accountant, Edward Craven-Walker, and marketed under the name Astro Lamps. The name might have changed since then, but the chemistry largely hasn’t.
The whirling globs we remember are made mainly of paraffin wax, with compounds like carbon tetrachloride added to increase its density. The liquid the wax floats in can be water or mineral oil, with dyes and sparkles added for whimsy.
So what causes the wax to float and fall? When the lamp is turned on, the incandescent light bulb in the base begins to heat the interior of the lamp. The wax expands when heated, and since density is equal to mass divided by volume, when the volume increases, the density of the wax decreases, and it floats.
When the ball of goop reaches the top of the lamp it cools down, decreases in volume and thus density, and falls back to the bottom to begin its journey again. A veritable Sisyphus of home decoration.
The exact composition of the wax and liquid are trade secrets, but they’re constantly being improved on. You can make a basic lava lamp at home with just oil, water and aspirin.
The newest innovation in the lava lamp legacy was the addition of ferrofluid. These liquids have microscopic magnetic particles suspended in them that allow you to interact with your lava globs with a magnet!
Besides mood lighting, lava lamps have also been used as random number generators. Programs were made to change the motion of lava blobs into truly random numbers, for use in cryptography. Whatever you use them for though, don’t drink them. Multiple people have been hospitalized for consuming the insides of these psychedelic accessories.