10 replies to this topic

[spectrum]

Can anyone shed any light on the formulation of "snow candles", these are devices which burn to produce ash resembling snow flakes, the devices are ignited and waved around to disperse the flakes in television and film productions where snow simulation is required.

I seem to think that the composition involved hexamine but I am not sure. I can't find anything on the net.

[pyrotrev]

I seem to remember it's metaldehyde that used for snow, presumably with a cool burning heat source: think smoke generators so maybe a KClO3/lactose mix??

[icarus]

metaldehyde used to be sold in white blocks abot the size of sticks of chalk it was used as a poison for slugs . Sometimes called meta fuel it burnt with a clean blue flame and was used as a fuel for model steam engines. If you bought indoor fireworks one of them was called snow storm it was small pieces of meta fuel you could see letters impregnated into the small piece confirming its origin .To make a snowstorm you had to press the metaldehyde against a hot metal surface not ignite it .a "smoke" of sublimed metaldehyde rose shortly followed by a snow storm of fine metaldehyde large snow "crystals" . it would be nessecary to heat metaldehyde without ignition to create a snowstorm . I would first however check on the toxicity of metaldehyde in the early 1970,s this wasnt so important!!!! some modern slug killers still use metaldehyde

[Gavin]

Ahh, that brings back memories icarus. Meta fuel and a hot tripod = 1 lab full of snow in short measure! If I remember rightly it made an odd squealing noise as the hot metal was pressed against the fuel block. Stinks as well!

[Mortartube]

How toxic is Metaldehyde? I belive that Metaldehyde tablets used to be sold in joke shops to put in the end of cigarettes to cause a snow storm. These were availbale still about 12 - 15 years ago, as I played a trick on my Dad with one.

If these aren't Metaldehyde tablets, what are they? I don't think the white flock they produce is magnesuim oxide or similar, it looks wrong.

[Firefiend]

Ellisdons Snow Storm Tablets

[Arthur Brown]

The whole point of Hexamine tablets as fuel is that they burn completely without melting, ash or smoke.

Meta tablets also burn as a solid fuel so lighting a mix with metaldehyde wouldn't produce "snow" from metaldehyde ash! Whether something sublimes to form the "flakes" under heat .....


Currently "snow" for movie use tends to be a potato starch based product applied through fan driven confetti blowers. I've seen pics of lawns buildings and vehicles "snowed" in this way. -and falling snow.

[spectrum]

The whole point of Hexamine tablets as fuel is that they burn completely without melting, ash or smoke.

Meta tablets also burn as a solid fuel so lighting a mix with metaldehyde wouldn't produce "snow" from metaldehyde ash! Whether something sublimes to form the "flakes" under heat .....


Currently "snow" for movie use tends to be a potato starch based product applied through fan driven confetti blowers. I've seen pics of lawns buildings and vehicles "snowed" in this way. -and falling snow.

I know of a company called "Snow Business", they pretty well specialise purely in the production of snow effects which are achieved in a number of ways. One of these is the pyrotechnic snow candle, I have seen one in the past. Very rough and amateur. Looks like a tube rolled (by a monkey with one hand around a sweetcorn mandrel!) using a whole sheet of white A4 photocopier paper. Inside I am sure there was a wrap of silver foil. It was so rough you couldn't see which end to ignite but, (2nd time lucky) we got it going and the chap demonstrating it to me dropped it into a metal bucket and proceeded to swing it around, the clouds of white ash flakes were VERY impressive, even up close they resembled snow to the extent that they were indistinguishable.

I would like to make them.

[pyrotrev]

Meta tablets also burn as a solid fuel so lighting a mix with metaldehyde wouldn't produce "snow" from metaldehyde ash! Whether something sublimes to form the "flakes" under heat .....

Sublimation is the whole point of it, metaldehyde does this at about 120 degC according to the trusty Rubber book, the key will be to exclude oxygen to make sure the stuff won't burn. It's exactly the same problem as making coloured smoke by heating dyes, hence the suggestion of the normal chlorate/lactose heating mix (roughly 55% KClO3 45% lactose), with a goodly amount of metaldehyde, probably at least 1:1 with the heating mix to keep everything cool. The indoor firework I remember was a little foil wrapped cylinder, maybe the use of a foil container helps keep atmospheric oxygen out? Otherwise a cavity above the mix and a fairly small exit hole might do the same thing.

[BrightStar]

Currently "snow" for movie use tends to be a potato starch based product applied through fan driven confetti blowers. I've seen pics of lawns buildings and vehicles "snowed" in this way. -and falling snow.

Fascinating stuff - the sublimated metaldehyde is new to me.

I recently saw a touring production by the RSC where they conjoured up a snow storm on stage with aqueous foam machines. It was very authentic, looking almost crispy in the air and proceeded to slowly 'melt' throughout the scene. The effect was quite mesmerising, helped by their lighting director absolutely nailing the 'cold winter morning' ambience.

For movie work it seems that you generally need less snow than on stage. If you try to film in a real snow storm the visibility beyond a couple of metres gets prohibitively low. You generally only need a light flurry in front of the actors. I could see that a slow burning pyro snow candle could be very useful for this kind of use outdoors on location.

[Mumbles]

Metaldehyde is a polymer of acetaldehyde. It's probably somewhat not good to breath in. It's one of the breakdown products of ethanol in the human body. Responsible for the sickly sweet taste in your mouth after a night of over consumption. Presumed to be partially responsible for the hangover. One of the other polymers of acetaldehyde, paraldehyde is a scheduled narcotic. Sleep agent I believe.