Lights, camera, action! The curtain rises and the theatrical story begins…

In present day 2009, when computerised technology and stunning special effects are at their most advanced, what better time to look at a much simpler, yet equally enigmatic piece of aesthetic artistry.

At the height of the festive season too, when here in the Western world (and especially so in the UK) it’s the pantomime period and cries of “Oh no he isn’t!” fill the air, this is remarkably relevant.

Television screens are adorned with premieres of blockbuster movies and network debuts of dedicated Christmas TV productions – all of which could have involved the use of CO2 technology at some juncture.

Having painted the scene, the stage is set… Ladies and Gentleman, we bring you the star of the show - dry ice!

Solid carbon dioxide and commonly used as an effective cooling agent, dry ice sublimates and changes directly to a gas at atmospheric pressure. Such a rapid and almost breathtaking visual effect makes the application of dry ice so popular on both the stage, and the silver screen too.

This popularity extends to parties, nightclubs and ‘haunted house’ rides or attractions, so functional is the application of this readily manufactured product. So what’s so special about dry ice in the theatrical realm?

Scientific, yet simple
Carbon dioxide (CO2) is much maligned and often the victim of a bad press, yet most of us are likely to have been an impressed onlooker of dry ice at some point in our lives, wowed by its imagination-induced smokescreen.

So what is dry ice and why is it so widely used?

Appearing as a translucent white solid, dry ice is solid CO2 made by compressing and cooling gaseous CO2 until it liquefies. Expansion then converts the CO2 into a snow-like form, before a hydraulic press compresses the ‘snow’ into one of three forms - either dry ice blocks, pellets, or slices.

Utilised for the way in which it sublimes from a solid state directly into a gas with such stunning, dramatic effect, dry ice is able to change from a solid to a gas at normal temperatures, without going through a liquid phase and therefore ensuring no mess nor moisture is left behind.

The fog descends…or rather, ascends
Often used to recreate the illusion of dense fog in theatre productions, CO2 is capable of dramatic effect like no other theatrical tool.

Unlike most artificial fog machines, which force the fog to rise up like smoke, fog from dry ice adds an almost ethereal edge as it crawls along the ground and circles around the ankle.

This dense cloud of fog is created as dry ice in water (inside a given machine) and sublimation is accelerated – an application not uncommon at theatres, discos, so-called ‘haunted’ attractions and nightclubs.

One of the greatest and most renowned theatre shows is the Phantom of the Opera, a hit on the silver screen too. The play has a number of touring productions, one of which has been on the road since 1992 and in recent years celebrated its 6,500th performance.

Each year that tour hits as many as 12 cities and amazes its audience with several scenes of a fog-shrouded lake, and a number of hold-your-breath moments.

It’s thought that up to 500 pounds of dry ice are required for each performance, to provide the eerie atmosphere of several scenes. Around six dry ice machines are required on stage for each rendition, refilled at intermission/interlude and consuming a varying amount of dry ice.

Exactly how much dry ice is needed is thought to depend on the size of the crowd and ambient temperature both inside and outside the venue.

It’s not just there that the use of CO2 in theatre is effective, a variety of other stage show productions are believed to employ CO2 shroud effects.

A fog is often created by pumping a blend of glycol or glycol/water mixture, referred to as fog fluid, into a heat exchanger and heating it until the fluid vapourises – creating a thick transluscent or opaque cloud.

Such fog machines are commonplace during stageshow productions, though several manufacturers of theoretical fog fluid have developed specially formulated mixtures designed to be used with CO2, with the intention of providing thicker, slicker and more consistent fog effects.

The specifically formulated fog fluid creates a denser mist than regular fog fluids, ensuring a thick fog which stays within just a few feet of the ground. Quite how long this aesthetic lasts is usually determined by the heating cycle of the fog machine and also the consumption rate of the liquid CO2.

When attempting to create a ‘magic’ reveal or disappearance of a character or act, liquid CO2 might be used on its own to create an atmospheric effect. Solid CO2 or dry ice is perhaps more frequently used in theatrical applications, as resident gasworld Technical Writer and CO2 expert Sam A. Rushing summarises.

He commented, “Many such theatre settings, such as plays, ballets, those which are not of a permanent nature but seasonal, would be perhaps better suited to using CO2 in the form of dry ice - often using a specific stage equipment set for CO2 which would then enhance the sublimation and ‘fog effect’ as well as adequate circulation and exhaust.”

“So CO2 is then a good tool for this purpose and remember, since it is heavier than air, it drops to the floor where it is being applied; thus specific entertainment and theatre settings could use this effect most suitably.”

“[Especially so] should the set design be compatible with the ‘falling or dropping’ effect of the CO2 vapour – thus appearing to be a fog-like environment - or seeking to produce a specific cloudy look in some cases.”

So how is this cloak of fog created?

The dry ice effect can be created by heating water to levels close to boiling point in a suitable container, such as a large drum with heating coils incorporated, and then carefully dropping the selected amount of dry ice blocks inside. As dry ice is an unstable liquid at standard pressure, the CO2 therefore sublimates and provides an instantaneous gas – subsequently providing a thick, white fog.

Using a fan placed at the top of the drum, the blanket of fog can be directed wherever it is desired – appearing as an entity of rolling fog that lay close to the ground as if by spooky magic.

On the silver screen
Furthermore, CO2 and related technology has been utilized in the production of blockbuster movies down the years, spanning genres as diverse as horror, thriller and action/adventure.

How many times have we all seen a chilling horror movie where a blanket of dense fog masks the impending doom that lies ahead? Or where the dreaded ‘thing’ type creature emerges from a thick fog-covered lake or pool?

In many of these instances it’s a safe bet to suggest that CO2 or some variation of CO2 technology has been implemented to create the illusion.

As well as the horror genre, CO2 technology is likely to be just as much a proponent in the sci-fi sector too.

Popular cult TV drama and Bafta Award-winning programme Doctor Who is known for its suspense, high drama and special effects. Largely regarded as ‘must-see’ TV on UK screens, Doctor Who is known to be a user of CO2 smoke or fog machines for its out-of-this-world experience and dramatic scenes.

On the less permanent setting of a movie set or feature film, CO2 gas might be used after being flashed from liquid, using high or low pressure portable tanks. While there are obvious health considerations to be taken into account, Rushing agrees that CO2 vapour would be a commonly used technique on the silver screen.

“Of course, in the production of movies, CO2 vapour as a fog is most suitable. However, we all must remember that excessive CO2 in any such setting can cause difficulty in breathing; or the worst case scenario, an asphixiant.”

“I am sure that for the use of CO2 in the movie production industry, large theatre productions and significant amusement parks have taken such precautions for sufficient ventilation – thus making the environment safe, creative, and fun.”

“In the year-round case, perhaps larger low pressure bulk CO2 tanks would be used onsite, if the entertainment facility were to create the ‘fog’ effect for an entertainment setting.”

Having perhaps lifted the veil a little on the unique use of CO2 or dry ice in the entertainment industry, it’s now time that we exit stage left and retreat back to our respective holidays.

May we send our good cheer and wish everyone Season’s Greetings from all at gasworld!!