Dry Ice, Smoke, Low Fogger and Co2
This article is to explain the difference betweeen these different effects.
As with many of my articles I am again aiming to de-bunk common mis-understandings of different production concepts. I regularly have clients request an item by name when they are actually looking for something different. This can result in them or their client not getting the perfect solution and a possible waste of money.
So in this article I will explain the difference between all these items and how each is used. I will keep this article to basic principles which may, in some cases, mean oversimplifying concepts. So if you require indepth technical information on any concept I suggest you do further reading.
Smoke machines create a cloud of smoke that lingers in the air and is often used to accentuate lighting effects or as a theatrical effects. The smoke fropm conventional smoke machines is created by the smoke fluid (a slightly oily transparent liquid) being pumped to hit a hot plate which vaporises it in a white smoke. In recent years smoke is used less on live events as it is quite visible in mid-air which can prevent clear sight around a venue.
This type of smoke does not look good on camera either. At SXS we only really use conventional smoke machines when we need a large volume of smoke very quickly, such as on outdoor performances, or where an 80s-style dancefloor effect is needed.
Smoke particles are quite large and can quite easily set off smoke alarms in venues which is another reason we minimise their use.
Smoke hangs in mid-air and does dissipate eventually.
Have is much like smoke but much more discreet, The particles that float around the air are much smaller. This means that you dont see the smoke in the air as much while it is still highly effective in light beings being visible. In many cases haze is completely invisible until a light shines through it. Haze is the standard for modern performances and concerts that are to be filmed or televised.
Haze machines are less likely to set off fire alarms which is also helpful. It is a common misconception that haze machines DONT set off fire alarms - this is untrue and I have seen them set off alarms in the past.
Haze tends to hang in mid-air and does dissipate eventually.
Dry Ice andPea Souper
Dry Ice is the solid form of carbon dioxide (CO2) and looks liek frosty ice. When it is dropped in water it create a smoke that is very dense and has a tendency to fall to the ground in mid to high ambient temperatures.
A "Pea Souper" the a machine that is used in live events to help the smoke process. This is essentially a large kettle that keeps the water warm and allows the dry ice to be lowered in safely.
Dry Ice is extremely cold and is very dangerous if touched with bare-hands. It should only be handled by competent and experienced live event technicians.
People often see dry ice effects on TV and want to create these effects for their events. Creating a dry ice effect on a large scale (such as on a large stage) can be very expensive to do as tyhe dry ice material is costly. Also, to get the effect that is seen on popular talent shows requires a very controlled environment where ambient temperatures are high and there is minimal air flow in the venue. Even the slightest air movement in a venue can whisk away the smoke effect.
As the smoke warms to room temperature the smoke disappears adn turns into invisible gas. There is no mid-air smoke which keeps the air-space clear
Refridgerated Low Fogger
The dry ice effect can be created by super-cooling smoke from a conventional smoke effect (see above). This can be done a small and basic level by simply pushing smoke through a bucket of ice and this is often done for amateur theatre shows. There are also professional refridgeration devices available that cool the smoke. These tend to be quite costly but can be effective in some environments.
The downside to this method is that, as the smoke warms, it rises and creates an appearance like a retro disco in the venue. For high-end production, televised events and top-tier theatre this is often not acceptable.
Co2 is often used to create a large, instant and high velocity jet of cold smoke. This is done by allowing free flow of CO2 gas from a gas tank. This can be used for stage smoke effects where residual smoke is inappropriate. It is also a great effect when sprayed onto a dancefloor (common practice in Ibiza) however there are concerns over the safety of this practice and we do not do this in the UK.