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Ask Doc Krock
The Science of Park Magic Explained
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Kevin Krock
It's beginning to look a lot like Christmas...
Have you heard that itís SNOWING nightly at Disneyland?!

A few weeks ago, someone mentioned to me that, following the Christmas fireworks, Disneyland was planning on having it snow in several places around the park, but nobody seemed to know how they were going to do it. The rumor was that the snow was not going to be frozen water, it was going to disappear before it hit the ground, and there would be no residue! It didnít sound like anything I had experienced before...

I did a little research to figure out how they were going to do this, but I came up empty handed Ė I couldnít find any "snow" making machine that met those requirements. I was going to have to rely on personal observation during the show.

On November 1, 2000, several of the MousePlaneteers met at Disneyland to watch the preview of Disneylandís Christmas fireworks spectacular. We all stood in the middle of Main Street, U.S.A. out in front of the Clothiers and watched the show. As the fireworks concluded and the park was still dark, we heard what sounded like a bunch of loud hair dryers start up from the light towers on the buildings. The lights slowly came up, and sure enough, it looked like snow was falling... in Southern California!

Doc Krock and son in the snow on Main Street, U.S.A.
Doc Krock and son in the snow on Main Street, U.S.A.

As the softly floating snow finally reached us, we noticed that they were actually tiny bubbles! That was the only clue I needed to figure out what was going on.

Here's a picture of the falling snow
Here's a picture of the falling snow

There are a few common ways of generating "theatrical" snow effects, but most of them require considerable cleaning efforts and pose safety hazards under Disneylandís conditions. Falling plastic and paper flakes look realistic, but they accumulate on the ground and cause a big mess and a slip- hazard. Real snow would be out of the question because it melts too fast and the residual water would make the "snow-zones" very slippery. You may not have thought about it, but it turns out that bubbles are the perfect solution.

Bubble Solutions

You may be thinking, "Arenít bubbles slippery and wet, too?" Most people are familiar with bubbles made from dish or hand soap and water, and those kind of soap bubbles do indeed have the same kind of problems as the other snow effects. However, as youíll see in a bit, bubbles can actually be created from many different types of solutions.

First, though, letís take a quick look at a typical bubble solution that you can buy in the store or make at home and what each component in the mixture does. For the usually desired big, long- lasting bubbles, there are three key components:

Chemical Functional Category Purpose in Solution
Water "Solvent" The main liquid that dissolves other substances to form a solution
Soap "Surfactant"
A substance that causes bubble film formation
Glycerin "Thickener" A substance that thickens the solution and increases bubble lifetime

The main problem with this type of formulation for "snow" making is that itís designed for big, long-lasting bubbles! These bubbles tend to pop and leave slippery residues on anything they land on. Also, because of the high water content (more than 95%), the bubbles also fall fairly quickly and donít really look like falling snowflakes.

What we want are small, "dry" bubbles that gently float around and last long enough to look like snow.

Bubbles have fascinated both children and scientists over the years, and a lot of research has been done on them. Much of the research has focused on making a wide variety of non- toxic bubble solutions that provide different special effects for use both at home and in industry.

For example, formulas for "indoor" and "vanishing" bubbles have been invented to provide non-residue or slowly disappearing effects, respectively. These are achieved by using lower amounts of water, different surfactants, and a variety of thickeners. However, when it comes to creating a "snow- like" effect, a couple of extra ingredients need to be included.

Letís take a quick look at one possible "snow storm bubble" formulation (Patent 4,246,717) that could be used at Disneyland:

Chemical Functional Category Purpose in Solution
Water "Solvent" The main liquid that dissolves other substances to form a solution
Surfactant Mixture "Surfactant"
A substance that causes bubble film formation
Glycerin "Bubble Stabilizer" A substance that increases bubble lifetime
Gelatin "Structural Support" A substance that helps provide a solid support to the bubble as the solvent evaporates Ė itís the stuff that makes Jell-Oô solid but rubbery
"Gelatin Stabilizer" A substance that increases the lifetime of the gelatin structure
"Film Enhancer" A substance that acts with the surfactant and gelatin to assist in the creation of bubbles

The first major difference between this formula and the previous one I described is the change in surfactant. Soap is one specific type of surfactant, but there are a lot of different surfactants with a wide variety of chemical structures and properties. By mixing more than one together, specific solution properties can be created that canít be done with soap. This added flexibility in the formula allows the solution to be adjusted for just the right effect, like very small, snowflake- size bubbles rather than huge, balloon- size bubbles.

The second difference is the addition of an amide film enhancer. These compounds work with the other substances in the solution to help form the thin bubble film. They also directly affect how the bubbles pop Ė with the amide, the bubbles slowly disappear, but without it, they simply pop and vanish.

The final difference is the addition of the gelatin and urea components. These help provide a structure to the bubble as the water evaporates. Once a bubble is blown, the water begins to evaporate, and usually, when the amount of water in the bubble film drops low enough, the bubble pops. However, if a solid gelatin structure gets formed when the bubble is blown, a thin shell will remain even after the water is gone. Itís this very light solid material that provides the snowflake look when the water has evaporated!

All of these additional of stabilizers and structural supports mean that less water can be used in the solution. This provides a "dry" bubble that, once blown, dries out fairly quickly, so there is very little residual water left when the bubbles are popped. Very low levels of water provide short-lived bubbles that pop shortly after being blown, and higher amounts of water increase the lifetime and, therefore, the distance that a bubble can travel.

At Disneyland, the bubbles are created pretty far away from the ground, so the formula is probably relatively wet since there is plenty of time for them to dry out. This extended lifetime also allows for a pretty convincing "snow storm" effect. If the bubbles dry out too fast, the "snow" would appear to stop several feet above the ground, and the illusion of snow would not work. But, when the water is balanced correctly, the bubbles float around and fall all the way to the ground just like real snowflakes.

Additionally, when the bubbles finally dry out after about 10 Ė 20 seconds, all that is left floating through the air is the lightweight, solid, bubble- shaped gelatin structure. This shell simply disintegrates upon touch leaving NO RESIDUE! To give you an idea of how much solid material is in these bubbles, you would need about 10,000,000 snow bubbles to generate about one ounce (around the weight of three Oreoô cookies) of dry residue, and since that many bubbles would be spread over a wide area, the residue would not be noticeable.

Now that we have a snow fluid that will provide a realistic looking snow flurry and that is completely non-toxic, safe, and completely cleanup- free, letís move on and take a quick look at how to actually generate these little nightly blizzards all over the park.

Snow Machines

Based on what we just discussed, we know the "snow" is really a lot of tiny bubbles, so it is pretty clear that the loud "hair dryer" sound we heard after the fireworks was the bubble generators creating and blowing the bubbles. When I first thought about it, I pictured the fan blowing on a bubble wand or something similar to that, but that system only works for generating a lot of relatively large bubbles.

Doc Krock's Park Pursuits:
Look around Main Street, The Hub, and New Orleans Square, and see if you can find the snow machine boxes.

They look like these:

small world way
This one's on small world way...

In front of Sleeping Beauty Castle
...the units above are in front of Sleeping Beauty Castle

From the outside, it's pretty tough to tell what is going on inside!

Also note how each box is placed on a light pole or light array - this allows the snow to be backlit at night, which makes it easier to see.

It turns out that snow machines are a little more complicated than a regular bubble machine (and quite a bit more expensive)...

First of all, thousands of very small bubbles, around 1/16 to 1/2 inch in diameter, need to be generated at a rapid and consistent rate. One of the ways to achieve this is to use a special nozzle. The figure below is a diagram of what this kind of bubble nozzle looks like:

Diagram of one type of snow bubble nozzle

Diagram of one type of snow bubble nozzle

The innermost tube provides the air that blows the bubbles. Around that tube is another tube that provides a constant flow of snow fluid that is delivered by a small pump. As the snow fluid reaches the end of the tube, it covers the air tube and gets blown into a bubble. The air and fluid flow rates can be adjusted to provide a range of bubble sizes and creation rates. The outermost tube is used for blowing the snow bubbles out of the machine and sending them flying out several feet away. The fan that supplies the air for this part of the machine is the one that sounds like a really loud hair drier. Once the bubbles are blown out of the machine, they catch the air currents and gently float towards the ground.

In the shot above you can see the blowers at work
In the shot above you can a blower at work

With this kind of nozzle design, a lot of snow fluid can get used up quickly, so a large supply of fluid must be stored in the generator. Most commercial machines can hold over one gallon of snow fluid, and that will last approximately 30 Ė 60 minutes, depending on how much snow is needed.

"Can I get one of those?"

As I mentioned earlier, Iíve spent quite a bit of time doing research on this effect, and it has become quite clear that bubble-based snow machines are widely available for purchase or rent. Just about every DJ supply site that sells lights, fog machines and bubble machines also sells some sort of snow machine and snow fluid. However, they are pretty expensive, and prices can range from around $500 to $1000 per unit! The fluid is also fairly expensive, with prices ranging from $20 to $45 per gallon.

If you have the money and really want it to look like itís snowing at your next holiday party, now you know how to take a little bit of the Disney magic home!

Don't forget to send email to Ask Doc Krock! at

Until next time...
Keep your eyes and minds on the magic!


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