Tech Talk: Event Planner's Guide to Fog, Haze and Smoke
Producing fog has many technical variables. Cut through the fog with this discussion of some of those differences.by Warren K. Kong | Published in April 2009 special effects | tech talk | technology | Departments
Q: When it comes to fog, what is the difference between oil-based, water-based and CO2?
A: Foggers, hazers, smoke machines — this simple item seems to be a sore subject with every planner, DJ and banquet captain, each of whom has their own way of dealing with them. I’d like to shed a little light on the subject.
First, what exactly is a smoke machine? Smoke is a cloud of fine particles suspended in gas, so any device that puts out such a cloud is, technically, a smoke machine. Since we associate smoke with fire and thus danger, however, the terms fogger and hazer are more common.
More important, though, are the types of smoke. “Black smoke,” usually created by the combustion of carbon, is deadly if inhaled for prolonged periods of time, such as in a fire. “White smoke,” by contrast, is a much lighter smoke that is safe to inhale and created by artificial means, such as foggers or hazers.
So what’s the difference between a fogger and a hazer? Foggers generally put out a short, intense cloud of fog, while hazers put out a constant fog that is much lighter and less noticeable. For most applications where you need to have lighting beams and lasers in the air, hazers are preferable. Foggers are primarily used in situations where lots of smoke is needed in a specific location and for a short period of time, such as a product reveal. For many outdoor events, foggers are preferable due to their high directional smoke output.
As for fluids, all on the market today, oil- or water-based, are safe to ingest and inhale. If you encounter a machine (usually a hazer) that is cool to the touch while operating, the fluid inside is likely oil-based. Fluid used in foggers that get hot to the touch (heater-type foggers) is water-based.
While oil-based fluids are perfectly safe for humans and animals, the same cannot be said for equipment and floors. The fluids will not harm or damage them, but after prolonged exposure, a thin film of oil will build up, affecting the functioning of parts and the safety of flooring.
Heater-type foggers are much like teakettles. As the water boils, the fog fluid is atomized into the air along with the steam. When the steam cools, the fog stays in the air.
CO2 is often used when a small burst of white cloud is needed for a short period of time. This effect has little or no lasting effect beyond the initial cloud of smoke. CO2 is also used to create a low or rolling fog effect. This is created when the smoke from a fogger is super-cooled as it exits the machine. Since the air around the fog and the fog itself are colder than the surrounding area, the fog sinks to the ground to create the effect — perfect when you need rolling fog, cloud looks or jungle themes.
Haze and fog are great effects when used properly. By knowing the ins and outs, you can stop costly mistakes when your lighting or laser vendor cannot do an effective job due to smoke regulations at the venue. There is no value to a laser show when there is no smoke, nor can you create a high-energy dance party when the lighting beams cannot be seen in the area.
As you can see, there are many pieces to the fog equation. Hopefully I’ve given you enough knowledge here to understand what it’s all about. And as my favorite action figure says, knowing is half the battle.
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