Glossary of Technical Theatre Terms – Theatrical Effects

Transformation from a scene downstage of a gauze to another scene upstage, by slowly crossfading lighting from downstage to upstage. If a gauze is lit steeply, or from the sides, it will appear solid. If this light is turned off and light added to the set upstage of it, it will disappear.

Metal bin or box covered with fine mesh in which Theatrical Maroons can be safely detonated.

Pyro: Coloured Smoke (Le Maitre) Pyrotechnic device, produced by Le Maitre, which is available as a cartridge which plugs into a flash pot, and when detonated, produces an intense cloud of coloured smoke. Care must be taken as the smoke contains a pigment which can stain light coloured objects or costumes.

Physical Effects:
Animation Disc
: A slotted or perforated metal disc which rotates in front of a lantern to provide 'movement' in the light. Most effective when used in front of a profile carrying a gobo.
Effect Disc: A painted glass disc rotating in front of an effects projector with an objective lens to focus the image (eg Flames, Rain, Snow).
Flicker Flame: Irregularly slotted rotating metal disc through which light is shone onto a prism-type piece of glass which scatters the beam of light and adds the 'dancing' effect of firelight to a scene.
Gobo Rotator: Motorised device inserted into the gate of a profile lantern that can be remotely controlled to rotate a gobo, usually with variable speed and direction.
KK Wheel: Slotted metal disc which rotates in front of a lantern to break up the light and provide movement. (Flicker Wheel)
Lightning: Created through the use of strobe sources or LED floods. Photoflood lamps were used in the past, but have a very short life, and aren't as bright as the other options.
Tubular Wave Ripple: Horizontal linear lamp around which a slotted cylinder is rotated providing a rising light (as reflected from water onto the side of a ship).
Programmed Effects:
Most modern lighting desks (and some very old ones) have the ability to add 'movement' to lighting states by changing the lighting states in various ways. These effects can be set up to run at the press of a button, or can start or stop when a particular cue is run. 
Chase: A number of different 'steps' are added which are then repeated until the chase is stopped. 
Flicker: Particular channels are set to randomly move between levels, with adjustable timings and other parameters.
See also: Pyrotechnics
Lighting Effects
Fog, Smoke & Haze On Stage

Emergency Stop button on Impressario automation control desk Also known as E-STOP, all scenic automation or powered flying systems have an emergency stop facility built into them. The pressing of any e-stop button in the system will immediately halt any movement and prevent any further movement until the system is reset.

Flash Pods for use with the Pyroflash system (Le Maitre) A small box containing the socket into which a pyro cartridge is plugged. Also known as a flash pod or firing pod.
German: Startbox

A generic term for a pyrotechnic device consisting of a small cylindrical container into which pyrotechnic powder has been loaded. At the bottom of the container is an electric match or igniter which, when a large enough electrical current flows through it, produces a spark which ignites the powder. Many companies (such as Le Maitre and Theatre Effects) produce cartridge flash pots which are pre-loaded and sealed, reducing the likelihood of incorrect usage.

Worn by actors who have to 'fly' as part of the action of the play (typically in Peter Pan or pantomimes). The flying harness is expertly fitted to the actor, and is fully tested and certified as safe before use by professionals. Cables attach to the harness normally at the hip, or the middle of the back, via a quick release locking snap hook mechanism. There are companies who specialise in this sort of wire work, and there's no excuse for not using the professionals at all times. See also KIRBY WIRE.
Flying by Foy website
Kirby's Flying
Aerial Effects website

Cloth with a relatively coarse weave. Used unpainted to diffuse a scene played behind it. When painted, a gauze is opaque when lit obliquely from the front and becomes transparent when the scene behind it is lit . Many different types of gauze are available;
Sharkstooth gauze is the most effective for transformations, because it is the most opaque.
Vision gauze is used for diffusing a scene and for supporting cut cloths.
HoloGauze™ is a metallised gauze optimised for front projection holographic illusions.
Also known as a Scrim, American Mesh.
Gobelin Fabric is used for tapestry making and has a less coarse weave than theatrical gauze, but will work for smaller shows. 
Voile / Net curtain material will work well and takes projection very well (as the thread is much finer than cotton gauze). 
See also Lighting With A Gauze / Scrim


Method for dropping a cloth from a flying bar. It consists of a bar which attaches to a standard flying bar, and is able to spin around. The bar has prongs welded to it on which the drop is hung (drop has grommetted holes in the top which hook onto the prongs). Normally these prongs are above horizontal, so the drop stays hung. On cue, the pole is rotated so that the prongs point downwards, and the drop consequently falls.

Wire used to fly an actor.
Named after George Kirby, who devised the first pendulum artiste flying system (in 1898). His company Kirby's Flying Ballet is still supplying flying equipment now.
Kirby Flying - History page

(Manufacturer) UK based manufacturer of pyrotechnic devices (Pyroflash brand name), smoke machines and other theatre effects
Le Maitre website

An electrically detonated pyrotechnic device giving the effect of a loud explosion. Made from gunpowder encased in stout cardboard or string. Must be used within a metal bomb tank. Originally developed in the second half of the 19th century to simulate the sound of cannon, it was often used to call out the volunteer lifeboat crew in an emergency.

A manual or electrically driven system for lifting performers off the stage and allowing spectacular stunts and aerial sequences to be performed.

Pyroflash System Controller (Le Maitre) A range of pyrotechnic cartridges, fliring pods and controllers used to create pyrotechnic effects in semi-professional situations, made by Le Maitre.

(often shortened to just 'Pyro') Chemical explosive or flammable firework effects with a manual detonation. Usually electrically fired with special designed fail-safe equipment.
There are many different variations of pyrotechnic effects available. The categories are as follows:
Theatrical Flash - a flash and a cloud of smoke
Maroon: produces a very loud bang. Must only be detonated inside a bomb tank covered with a protective mesh.
Gerb: version of the Roman Candle firework, throwing a shower of sparks into the air. Possibly named from the French 'Gerbe' meaning a sheaf of wheat, due to it's shape.
All pyrotechnics should be used with close reference to local licensing laws, and the manufacturers instructions. Professional advice should be sought before the first use of effects.
Some territories only permit licenced pyrotechnicians to use these devices.
The word originates from the Greek for fire, pyr

Pyrotechnic effect that produces a flash, short burst of sparks and a small cloud of smoke. Can be used to simulate an electrical fault. 

Pyro: Silver Jet (Le Maitre) Pyrotechnic cartridge produced by Le Maitre, which produces a bright shower of sparks in a fountain. This is a type of GERB.

A pyrotechnic product which produces a cloud of real smoke when set alight.
Also known as a Smoke Pellet. 

Pyrotechnic effect that creates a focussed burst of sparks from a small tube. 

Pyro: Theatrical Flash Large (Le Maitre) Pyrotechnic cartridge produced by Le Maitre, which produces a bright white flash, a small bang, and a large mushroom of smoke.

An instant scene change, often effected by exploiting the varying transparency of gauze under different lighting conditions.
See also Lighting With A Gauze / Scrim

UV Cannon by Prolight Concepts, UK Short wavelength source of light at the end of the visible light electromagnetic spectrum which causes specially treated materials to fluoresce on an otherwise blackened stage. Used for special effect and for lighting onstage technical areas (eg Fly Floors). Ultraviolet sources designed for stage use are known as Black Light sources and have all harmful radiations filtered out. They produce UV-A radiation, which is also present in sunlight, and is invisible to the naked eye;  in black light sources, the amount of UVA is far lower than you'd experience outside. UV-B radiation is far more harmful, and is not present in black light sources.
However, some high-intensity black light sources can be harmful to the eye so must not be used at close range to people, or where people could face the light source for any more than a few minutes. Use them to light scenery or props, or performers at a safe distance.
Black Light is used extensively in the Czech Republic where stunning effects are achieved on stages lined with black velvet. See the Image Theatre website for more.
Image Theatre website