Evaporative Snow ™
To properly understand the best ways to incorporate evaporative snow into your production design, you must first understand exactly what it is and how a snow machine works.

If you look closely at the "snow" produced by an evaporative snow machine, you will notice the flakes are essentially small clusters of tiny bubbles, like very fine soap suds. Bearing this in mind, let's take a closer look at the internal workings of a snow machine.

All snow machines are essentially made up of several basic parts. The snow starts as a "snow fluid" in a reservoir or bottle usually found at the back of the machine. A small plastic "feed tube" takes the fluid from the reservoir to a small nylon "sock" at the front of the machine by means of a pump. The sock is mounted to the front end of a high output blower. The material is a very finely woven mesh, which acts like hundreds of very tiny bubble wands producing the "flakes" you see. The "flake size" control varies the speed of the pump, and therefore the amount of fluid reaching the sock. More fluid results in more and larger clusters of bubbles.

This flake size is the key to making any evaporative snow truly evaporative and residue free. Ideally you want to set the flake size so that the snow evaporates just as the snow hits the ground. Imagine, for a moment, blowing a traditional soap and water bubble with a bubble wand. The air pressure in the bubble is greater than the surrounding air pressure, which keeps the bubble inflated, much like a child's balloon. Assuming air currents keep it aloft and no one breaks it, it will remain intact until enough water evaporates from its surface that the film can no longer maintain surface cohesion, and the bubble's internal air pressure causes it to burst. In other words, it dries out. As it does so, the walls get thinner until they are not strong enough to contain the pressure, and the "balloon" pops. While evaporative snow liquid does contain water, it also contains evaporatives to make the "flakes" disintegrate more rapidly. This setting produces a very esthetically pleasing and moderate snowfall. While you can certainly create a blizzard effect with these machines, additional safety factors must be considered, as the snow will build up on the floor or stage producing a very slippery surface. If build up on the stage is a desired effect, consider using a traditional shake bag with potato flakes or plastic flakes in addition to an evaporative system.

There are several important factors to consider, from a design aspect, when using snow in any production. First, all snow machines produce a "cone" of snow, which is smallest near the machine and disperses as you get farther away from it. That snow is considered a "curtain effect". This means, if you lay down a "curtain" of snow (just upstage of the proscenium, for example) anything moderately upstage of that snow curtain will appear to be snowed upon, assuming the snow is not allowed to build up on the ground. You can increase the overall affected area through the use of judiciously placed fans, both near the machine and on the ground. Fans near the machine (some larger machines have these incorporated into their design already) will help disperse the snow into a larger area. Fans on the ground will also help with dispersion, as well as provide beautiful updrafts and swirls. These machines are often used in ballrooms for holiday parties or occasionally even in arenas. The key to coverage in a larger venue (or even if you want to make it snow on your audience at a theatre) is not as much in the number of machines as the air handlers in the room itself. Air handlers in arenas and many modern ballroom facilities are designed to re-circulate thousands of cubic feet of air per minute. As we are on the ground, and the air handlers are high above us, we don't often feel the air currents in the room, but they are up there (right by where you hang your snow machines). With a little bit of experimentation, these air currents often do a wonderful job of helping to circulate snow around the venue. Another great technique for getting a nice swirling effect around a room involves staggering the placement and alternating the direction and side of the venue of the snow machines, so that the edges of the air streams from the machines interact in opposing directions.

One of the biggest challenges, and most often overlooked factors when using snow, is proper lighting. Back lighting, and to some extent side lighting, are vital to the audience being able to see a snow effect well. If lit from the front only, the effect's visibility will be poor at best. Lighting can be especially challenging in a ballroom or other "total environment" setting or venue, when your audience will be viewing the snow from multiple angles and positions in the room. Ideally, you want your lighting to come from above, yet below the snow machines, hiding the snow machines in the dark above the light sources, hiding the source of the snow, and adding to the sense of wonder this effect often has on an audience.

A final consideration when using evaporative snow is the noise the machines make. To a large extent, it can be covered with music. However, our company has developed a quieter snow machine using better sound insulation and more quiet blowers. This new and improved style of machine is called the T-1600 series.