How Liquid Motion Lamps Work

The most common way to change the density of compounds is to change their temperature. Heating a compound activates the molecules so that they spread apart, making the compound less dense. If you have read How Thermometers Work, you know that heating water causes it to expand quite a bit. Cooling the compound down again increases the density.

If you look inside a motion lamp when it's turned off, you'll find a solid waxy compound on the bottom of the globe. This solid compound is only a little denser than the surrounding liquid compound. When you turn on the light at the base of the globe, here is what happens:

This is a pretty simple idea, but it's actually fairly complicated to balance all the elements -- the compounds, the heat source and the size of the globe -- so that the blobs are constantly moving around. In fact, the companies that produce commercial motion lamps guard their ingredients very closely, and motion lamp enthusiasts have had a very hard time reproducing the displays you see in commercial models.

In the next section, we'll look at the history of the liquid motion lamp.

The invention of this type of motion lamp is generally credited to a man named Edward Craven Walker, although there is a certain amount of controversy surrounding its actual origins. One widespread account is that Walker came up with the basic design in the 1950s while developing a complicated egg timer in England. Another version of the story is that Walker got the idea from a simpler liquid motion lamp he saw in a pub. In any case, Walker was definitely the man who molded this idea into its current form and started it on its way to becoming a popular cultural icon. Walker died in August 2000, at the age of 82.

Walker worked on his motion lamp, which he called the Astro Light, for almost a decade before finally launching it in 1963. His U.K.-based company, Cresworth, achieved some success with the device, but the lamp design really took off when the U.S. company Lava Manufacturing Corp. formed in 1965. The company was founded by two Chicago entrepreneurs, Adolph Wertheimer and Hy Spector, who discovered Walker's Astro Light at a trade show in Germany. They acquired the U.S. patent rights and began producing a line of their own motion lamps. These lamps soon caught on as a must-have decoration for the counterculture crowd.

This company, now called Lava World International, still produces almost all of the commercial models sold in U.S. stores. Their product is called a Lava Lite^®, not a Lava Lamp, but both terms are trademarked. Like Xerox and Kleenex, "Lava Lamp" is commonly used as a generic term, but intellectual property law does not recognize it as such. Lava World International closely monitors how publishers print the word "lava" in connection with motion lamps.

When the Lava Lite caught on in the United States, Walker's Astro Light grew in popularity in Europe. Sales dropped off in the 1980s, however, and Walker sold the Astro Light rights to Cressida Granger. Her company, Mathmos, continues to produce lamps for the market outside the United States. The company has expanded its line considerably over the years, offering many innovative, modern variations on the basic lamp design.

Both Mathmos and Lava World International have enjoyed a "motion lamp renaissance" that began in the early 1990s as part of a 1960s nostalgia trend. Astro Light and Lava Lite sales are still going strong today, and there are lots of motion lamp fans out there, at least judging by the number of motion lamp sites populating the Web.

Next, we'll show you how to build your own liquid motion lamp.

There are a number of Web sites that offer instructions on how to create your own liquid motion lamp.

You won't find any plans with the exact same material found in a commercial lamp, because this information is still top secret. Motion lamp recipes are so popular because coming up with exactly the right compound combination is an exciting chemistry puzzle. It's a real trick finding two compounds that will form the free-floating blobs you see in commercial lamps.

One of the simpler plans out there uses mineral oil as the blobs and a combination of 70-percent and 90-percent rubbing alcohol as the surrounding liquid. The trick with these ingredients is to balance the two different grades of rubbing alcohol until you get a good balance between the alcohol's density and the density of the oil.

You can color the blobs by adding insoluble dye, such as the sort used in permanent markers. For best results, you should find a fairly tall glass container for the globe. For a safe and effective lamp, don't use anything hotter than a 40-watt bulb to heat the globe. To learn how to make this basic motion lamp, check out this page.

Other homemade motion lamp designs use more complicated combinations of materials to create better displays. In most cases, acquiring all the necessary ingredients for building a lamp yourself is actually more expensive than simply buying a commercial model. It is an interesting project, however, and it's an excellent way to fully explore how liquid motion lamps work.

If you are interested in making your own lamp, keep in mind that dealing with these sorts of materials and constructing any device with a heating unit is potentially hazardous. Don't undertake such a project unless you have a good knowledge of the materials involved or you are assisted by someone who does. Make sure you aren't handling any dangerous chemicals and, as with any chemistry experiment, wear eye protection and an apron. Most of the sites that feature motion lamp plans also include disclaimers disavowing any responsibility because they are fully aware of the potential dangers involved.

To learn more about the history and construction of motion lamps, check out the links on the next page. You'll also find plenty of pictures of the many commercial motion lamp designs released through the years.