Dear Cecil: When we are fortunate enough to discover someone willing to visit our excruciatingly drab apartment, a topic which invariably comes up is the nature and origin of our vintage red lava lamp. Just what is a lava lamp and how does it work? Is it the result of some ghastly industrial accident or did someone create it on purpose? Jim Geckle, Brian Repp, Tim Ray, Lindor Henrickson, Greenbelt, Maryland

Cecil replies:

As you know, boys, we at the Straight Dope strive at all times to be cool. However, nothing we have ever done even approaches the coolness of our latest feat, namely visiting the actual lava lamp factory, the source — nay, the font — of all the world’s lava lamps. (Actually, all the lava lamps sold in the Americas, but what’s a couple continents between friends?) It’s located in a funky old neighborhood in Chicago, has a front office staffed largely by little old ladies, and goes under the fittingly grandiloquent name of Lava-Simplex Internationale.

As Cecil’s more venerable readers know, the lava lamp was one of the three indispensable components of the properly furnished 60s apartment, the other two being a black-light poster and a waterbed. The lamp consists of a glass jar (technically known as a “globe”) filled with a colored liquid, at the bottom of which is a glob of the mystic lava lamp lava. When you turn the lamp on, the lava gradually extrudes into a long, obscene column that shimmies around suggestively and finally breaks into gigantic globules. The effect is bizarre and, as many veterans of the 60s can verify, is best appreciated under the influence of mind-altering drugs.

The lava lamp, properly known as the “Lava Lite,” was invented in England in the early 60s by one Craven Walker. History does not record what sort of twisted psychosexual impulse inspired Mr. Walker, although when you’ve got parents who would give you a name like “Craven,” we can probably guess. An entrepreneur named Adolph Wertheimer spotted the lava lamp, then called the Astrolight, at a Hamburg trade show in 1965, and immediately heard destiny calling. Together with partner Hy Spector, he bought the American manufacturing rights, set up a factory, and began cranking out Lava Lites by the boatload.

The timing could not have been better. The lava lamp immediately became one of the icons of the Age of Aquarius. Unlike many relics of that lost era, however, the lava lamp never entirely disappeared. It reached something of a low point during the recession of the early 80s, but now business is on the upswing, apparently because the children of the baby boomers are rediscovering the things that made the 60s great. Indeed, you can now get a lava lamp whose base is painted trendy matte black, the better to fit in with your halogen lighting and Bang & Olufsen stereo. Some may feel this at odds with the inspired tackiness that is at the heart of the lava lamp experience, but such is progress.

The principles of Lava Lite operation are simple. The “lava” is basically a specially compounded wax. When heated from below by a 40-watt bulb, it expands until it becomes less dense than the liquid above, causing it to rise. When it gets to the top of the globe, the wax cools and starts to sink again, and the cycle repeats. Convection currents in the liquid presumably add to the effect.

Sounds simple, but Lava Lite president Jack Mundy tells me that manufacturing the things is actually an exacting process. The wax and the water are composed of 11 secret ingredients mixed in giant (well, relatively large) vats. Dedicated technicians measure the specific gravity of the various components to the ten-thousandth. The specific gravities of each batch of wax and water must be individually matched, or the wax will break up into tiny bubbles, crawl up the side of the globe, or just float about an inch above the bottom of the lamp.

The custom mix-and-match involved in each batch explains why you can’t just go out and buy some replacement goo if the fluid in your lamp gets low or if the lava gets sick. But fear not — the Lava Lite folks will sell you a new globe for about $22 or so, depending on the size. (New lava lamps cost anywhere from $35 to $75.) If your lava lamp is so old that the right size globe isn’t available anymore, they’ll sell you a new lamp at a discount. Call (312) 342-5700 or write Lava-Simplex Internationale, 2321 N. Keystone, Chicago, IL 60639.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.