Since their first
appearance in the 1960s, liquid motion lamps have been a
familiar fixture in college dorms and teenager's bedrooms all
over the world. In the United States and many other countries,
the novelty devices have become completely entrenched in
popular culture! Even after all these years, people are still
buying motion lamps, and the major manufacturers now offer
hundreds of variations on the basic design!
In this edition of HowStuffWorks,
we'll look at these popular devices to find out exactly what
happens inside to produce such a mesmerizing display. We'll
also explore the history of liquid motion lamps a little, and
get you started on making your own basic lamp. The next time
you see a motion lamp, you'll definitely be transfixed,
because you'll know all about the amazing processes at work!
Inside the Lamp
Liquid motion lamps
are actually fairly simple devices. They are based on very
basic scientific principles and consist of only a few simple
components. They must have:
create the floating blobs, the two compounds in a motion lamp
must be immiscible, or mutually insoluble. All
this means is that liquid A doesn't dissolve in liquid B --
the two don't mix, so you see two separate liquids, one
floating on top of or within the other.
- A compound that makes up the floating "blobs"
- A compound that the blobs float in
- A lamp that illuminates the display and provides the
heat necessary to move the blobs
The classic example of immiscible compounds is oil and
water. If you fill a jar with common mineral oil and water,
you'll get a water layer with a layer of oil floating above
it. This combination of water and oil in a jar has a similar
look to a commercial motion lamp with its light turned
off -- in a cold lamp you see two separate layers.
The coolest thing about motion lamps, of course, is that
they produce distinct amorphous blobs that rise and fall in
the lamp's "globe" on their own. To produce this effect, you
need to pick your two insoluble compounds very carefully. In
our oil and water jar, the water ends up on the bottom because
it has a much higher density than oil. Simply put, a liquid
with a higher density pushes a lower-density liquid upward
(for more on this, check out How Helium
To get blobs that will float around, you need two
substances that are very similar in density. Then you need to
be able to change the density of one of the compounds so that
sometimes it is lighter than the other compound (and so floats
to the top) and sometimes it is heavier (so that it sinks to
the bottom). By having compounds that have similar densities,
the blobs can easily switch between rising and sinking.
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
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:
- The solid quickly turns into a liquid and expands,
giving it a lower density than the surrounding liquid.
- A warm blob is now slightly less dense than the
surrounding liquid, so it rises to the top of the globe.
- Because it is farther away from the heat source, the
blob cools slightly, becoming more dense than the
surrounding liquid (it does not cool down enough to change
back into a solid, however).
- The blob sinks to the bottom of the globe, where it
heats up enough to rise again.
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.
A Bit of History
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
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.
Make One Yourself!
There are a number of Web
sites that offer instructions on how to create your own liquid
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
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
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, as well as downloadable lamp
Lots More Information!
More Great Links