Fog, Haze & Low Fog: A Complete Guide for Stage and Event Production

Fog, Haze, and Low Fog: Three Different Effects

Fog, haze, and low fog are very different effects that require different fluids and often different equipment. Understanding the difference is essential for choosing the right atmospheric effect for your event production or theatrical performance.

Fog

Fog, as referred to in the event production industry, is an airborne smoke-like effect. Smoke consists of particles, while fog is vapor. This is created by vaporizing (utilizing heat) a mixture of purified water and poly functional alcohols, turning the liquid into an aerosol.

The effect can be anything from a quick burst which dissipates rapidly to a longer lasting, dense fog. The difference comes from the balance of chemicals used in the fog fluid.

Fog Fluid, sometimes called Fog Juice, consists primarily of distilled water in combination with other chemicals such as propylene glycol and/or triethylene glycol (TEG). When vaporized with heat, these chemicals produce tiny droplets. When they come into contact with cooler air particles outside the machine, it forms a cloud.

Haze

Haze is typically an atmospheric effect used for lighting enhancement. Everything from concerts to videography to laser shows utilize haze to capture light as it passes through the air.

Clean air does not contain sufficient particles to capture the beams of light, so a hazer or multiple hazers are deployed to provide a sufficient media. Moving lights and lasers would just be light on the ground or wall without haze. Ever seen a picture or video where you can see beams of light streaming through a window? That typically doesn’t occur without a small amount of haze in the air.

Types of Haze Machines

Haze can be produced three ways: with a fog machine utilizing a special formula of glycol fluid, with a specialized haze machine designed to vaporize glycerin-based fluid, or by atomizing food-grade mineral oil or a special water-based fluid with compressed air.

The fog machine style tends to hang in the air approximately 15 to 20 minutes, depending on air circulation and humidity. The glycerin formula haze machines tend to have a longer hang time. The pressurized air atomizer machines utilizing food-grade mineral oil tend to produce the finest haze with the longest hang time, up to 2 to 3 hours unless exhausted from the room.

Low Fog

Low-lying fog is a tough effect to produce efficiently. There are several methods, each with trade-offs.

Dry Ice

Dry ice is messy, expensive, often hard to find, and can be dangerous. Dry Ice is frozen CO2, and to get a good effect, it needs to be sublimated in hot (but not boiling) water. Great care must be taken when handling dry ice, especially when breaking it up into smaller chunks to achieve maximum surface area. Even a small shard can cause a burn on exposed skin. The water needs to be at 185 degrees F and kept as close to that as possible.

A lot of moisture typically comes with this method, which can leave a slick area where the fog is deposited on the stage. It is EXTREMELY important to remember that CO2 displaces oxygen, so never have actors or animals lay down in the fog.

Liquid Nitrogen (The Best Method)

The absolute best method of producing low fog is the Interesting Products Mammoth Fogger. This unit heats a large volume of water in a sealed vessel, and on cue, injects liquid nitrogen into the steam bath. It creates a magnificent effect, and since nitrogen is inert and makes up 78% of the air we breathe, it is totally safe. The downside is that the unit is quite large, requires 3-phase power, needs a water supply connection, and the liquid nitrogen Dewar can be consumed in 26 minutes.

Chiller-Based Low Fog

Most other “stage-friendly” methods of producing low fog include pumping quick-dissipating fog fluid from a regular fog machine through some manner of chilling device to cause the normally warm fog to be cooler than the surrounding air, so it stays low, and when it warms and rises, it dissipates. Several devices of this style are on the market from Antari, City Theatrical, LeMaitre, and Ultratec.

Atomized Water Method

The newest method on the market utilizes a mechanism to atomize distilled water and mix it with a small amount of quick-dissipating fog fluid. This is relatively efficient and inexpensive to operate. You might need more than one unit to fill a large stage, but it is doable for the price point and ease of use. We use a Chauvet Cloud9 for this method with great success.