Lycopodium powder is a yellow-tan dust-like powder, consisting of the dry

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...

s of clubmoss plants, or various fern relatives. When it is mixed with air, the spores are highly flammable and are used to create dust explosions as theatrical special effects. The powder was traditionally used in physics experiments to demonstrate phenomena such as

Brownian motion Brownian motion, or pedesis (from grc, πήδησις "leaping"), is the random motion of particles suspended in a medium (a liquid or a gas). This pattern of motion typically consists of random fluctuations in a particle's position insi ...

Composition

The powder consists of the dry

s of clubmoss plants, or various fern relatives principally in the genera '' Lycopodium'' and '' Diphasiastrum''. The preferred source species are ''Lycopodium clavatum'' (wolf's-foot clubmoss) and ''Diphasiastrum digitatum'' (common groundcedar), because these widespread and often locally abundant species are both prolific in their spore production and easy to collect.

Main uses

Today, the principal use of the powder is to create flashes or flames that are large and impressive but relatively easy to manage safely in magic acts and for cinema and theatrical

special effects Special effects (often abbreviated as SFX, F/X or simply FX) are illusions or visual tricks used in the theatre, film, television, video game, amusement park and simulator industries to simulate the imagined events in a story or virtual w ...

. Historically it was also used as a photographic

flash powder Flash powder is a pyrotechnic composition, a mixture of oxidizer and metallic fuel, which burns quickly and produces a loud noise regardless of confinement. It is widely used in theatrical pyrotechnics and fireworks (namely salutes, e.g., cher ...

. Both these uses rely on the same principle as a dust explosion, as the spores have a large surface area per unit of volume (a single spore's diameter is about 33 micrometers (μm)), and a high fat content. It is also used in

fireworks Fireworks are a class of low explosive pyrotechnic devices used for aesthetic and entertainment purposes. They are most commonly used in fireworks displays (also called a fireworks show or pyrotechnics), combining a large number of devices ...

and

explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An exp ...

s, fingerprint powders, as a covering for pills, and as an

ice cream Ice cream is a sweetened frozen food typically eaten as a snack or dessert. It may be made from milk or cream and is flavoured with a sweetener, either sugar or an alternative, and a spice, such as cocoa or vanilla, or with fruit such as ...

stabilizer.

Other uses

Lycopodium powder is also sometimes used as a lubricating dust on skin-contacting latex (natural rubber) goods, such as

condom A condom is a sheath-shaped barrier device used during sexual intercourse to reduce the probability of pregnancy or a sexually transmitted infection (STI). There are both male and female condoms. With proper use—and use at every act of inte ...

s and medical gloves. In

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which rel ...

experiments and demonstrations, lycopodium powder can be used to make sound waves in air visible for observation and measurement, and to make a pattern of electrostatic charge visible. The powder is also highly

hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, ...

; if the surface of a cup of water is coated with lycopodium powder, a finger or other object inserted straight into the cup will come out dusted with the powder but remain perfectly dry. Because of the very small size of its particles, lycopodium powder can be used to demonstrate

. A microscope slide, with or without a well, is prepared with a droplet of water, and a fine dusting of lycopodium powder is applied. Then, a cover-glass can be placed over the water and spore sample in order to reduce convection in the water by evaporation. Under several hundred diameters magnification, one will see in the microscope, when well focused upon individual lycopodium particles, that the spore particles "dance" randomly. This is in response to asymmetric collisional forces applied to the macroscopic (but still quite small) powder particle by microscopic water molecules in random thermal motion. As a then-common laboratory supply, lycopodium powder was often used by inventors developing experimental prototypes. For example,

Nicéphore Niépce Joseph Nicéphore Niépce (; 7 March 1765 – 5 July 1833), commonly known or referred to simply as Nicéphore Niépce, was a French inventor, usually credited with the invention of photography. Niépce developed heliography, a technique he us ...

used lycopodium powder in the fuel for the first internal combustion engine, the Pyréolophore, about 1807, and

Chester Carlson Chester Floyd Carlson (February 8, 1906 – September 19, 1968) was an American physicist, inventor, and patent attorney born in Seattle, Washington. Carlson invented electrophotography, the process used by millions of photocopiers worldwide. C ...

used lycopodium powder in 1938 in his early experiments to demonstrate

xerography Xerography is a dry photocopying technique. Originally called electrophotography, it was renamed xerography—from the roots el, ξηρός, label=none ''xeros'', meaning "dry" and -γραφία ''-graphia'', meaning "writing"—to emphasi ...

References

{{reflist Pyrotechnic compositions Powders