Project: Design and build a theatrical snow machine prototype.

We chose to investigate a snow machine as we produce a pantomime every Christmas and it would be an exciting addition to our technical repertoire.

The research falls into two areas: machines and material.

Machines

Some snow machines work by blowing detergent based foam. Others work by sprinkling some sort of solid dry flakes. We dismissed foam blowers because they are not really appropriate for the theatre - the foam would make the stage wet and slippy. Even if that were not a problem, blowers produce a jet of snow which would not give  the effect of snowfall across the whole stage

Drum/cylinder devices

These are basically rotating drums made of mesh and containing flakes of some kind. As the drum rotates, some of the flaves fall through the mesh, creating the effect of snowfall. They are usually motorised and the speed can be controlled, producing more or less intense snow.

Trough devices

These have a trough which is the full length of the device containing the flakes. The trough sits on top of a slowly rotating cylinder which has a non-slippery surface and which drags some of the material through a narrow apperture between the trough and the cylinder. Once again, regulating the speed produces heavier or lighter snowfall.

Snow cradles

These are the oldest and simplest devices around. A snow cradle is usually made out of a piece of muslin or other cloth with small holes, through which the flakes fall. The edge of the cloth is attached to two adjacent battens and filled with flakes snow is released by moving one of the battens up and down slightly to allow snow to filter through the holes.

We decided to go for a snow cradle as the first option. It is by far the simplest to make and if we can get it to work we could hang a battery of them across the full width of our panto theatre (13,5 metres)

Materials

As mentioned above, foam is used in snow blowers. Drums, troughs and cradles all use some kind of dry material, which may be made of paper, polystyrene or shredded polythene. The most common commercially available stage snow seems to be shredded polythene, which comes in fine and coarse varieties.

We dismissed polystyrene above all because inhaling its dust is a health hazard and we could not guarantee that our polystyrene snow would be dust-free. We were also concerned about it sticking to clothes and just generally being messy and inconvenient to handle. We decided to run tests with paper and polythene flakes in order to evaluate how easy it would be to produce them ourselves in the necessary quantities and, most importantly, how realistic they look in action.

Not-so-fun fact: When the Wizard of Oz movie was made in 1939 the fake snow used on set was highly carcinogenic asbestos! You can read more about this here.

 

Our first attempt at a snow cradle

We came across instructions online which suggested that we should use 6' (2m) width of cloth. Neverthelsess, we wanted to try with something much narrower, at least to start with. One reason for this is that our panto theatre doesn't have a fly loft and space above the stage is very resricted. Anything we install above the stage is potentially visible from the front rows, particularly if it is well downstage. So we decided to work with 60cm width, spacing our battens 15cm apart (so making a "trough" at the lowest point of the cloth with a 15cm diameter).

We attached the battens (broom handles) with staples and gaffer tape.

and marked out the area within which we would cut the holes. The holes go to one side of the centre, in a 20cm wide strip. the other side of the cloth is free of holes this part will form the trough when the machine is not active, so that no flakes escape.

We cut holes of about 1cm2 at regular intervals. Initially we wanted to test having a greater or lesser density of holes, although this idea changed slightly once we started to run tests.

 We also tried to make some polythene snowflakes from a white plastic bag. First we sliced strips with a cutter.

Scrunched them up a bit...

...and chopped them up into bits.

We made some paper flakes out of regular white photocopier paper in a similar way.

First test with polythene flakes

Basically nothing fell through the holes, although we had only made a tiny amount of material and we thought that might be part of the problem, so we decided to make more.

Second test with polythene flakes

Despite having considerably more material this time, very little made it through the holes.

Third test: paper flakes

Our first test with paper wasn't massively successful either. Most of the material just fell off the sides. At least both the paper and polythene flakes fell in a reasonably snowy way! The polythene floated a bit more and fell more slowly which seemed preferable.
At this point we decided to enlarge the holes in the cradle, basically joining 2 holes into one to make one long hole.

Fourth test: polythene flakes and enlarged holes

The larger holes did the trick! Material is still falling off both ends of the cradle and we need to find a way of blocking those openings. Some improvements to our polythene flakes still seem necessary too.

What's next?

• Cut more holes in the cradle, perhaps experiment with  having holes closer together/further apart.
• Block the ends of the cradle somehow.
• Develop the cradle from a hand-held device to one that can be suspended above the stage.