The smell and noise of Dry Ice
Nick Rothwell
machines work, and what exactly is it that comes out of them?
I was on stage a few weeks ago, and the rather over-zealous operator of
the machine insisted on spraying the stage (and us) with the stuff during the quiet parts of our music set (totally obliterating me from the audience,
I was later told...).
The first thing which struck me was the incredible racket the machine made
(louder than the foldback signal on our monitors, in fact), rather like someone driving a tractor across the stage behind us. Even a decent sized
fan wouldn't make that much racket.
The other thing is that the stuff smells of perfume. I've been to
several shows using dry ice, and it always smells the same (so it's not
some arbitrary choice of additive). Why?
I thought that these things just took frozen carbon dioxide (perhaps
under pressure) and brought it up to room temperature and blasted it out.
But, CO2 doesn't smell. Obviously, it isn't that simple. Can someone clue
me in?
I love the smell of the stuff, by the way...
--
Nick Rothwell, Laboratory for Foundations of Computer Science, Edinburgh.
ni...@lfcs.ed.ac.uk <Atlantic Ocean>!mcsun!ukc!lfcs!nick
~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~
"Now remember - and this is most important - you must think in Russian."
Geoffrey Kimbrough
In article <14...@skye.cs.ed.ac.uk> ni...@lfcs.ed.ac.uk writes:
>Something that's been puzzling me. How exactly do these dry ice
>machines work, and what exactly is it that comes out of them?
You can build one for a few bucks from easily obtainable materials.
Of course, that doesn't stop some theater companies (and especially
rock bands) from spending fortunes on them 8^). Basically you need
hot water, crushed dry ice, and some 6" drier-vent hose. Unless the
hose is *real* long, you don't need a fan. The ones I've seen had
a basket (possibly from a McD's frier) suppended from the lid of an
oil drum by a handle that could lower it from the outside (like a
plunger). The hose was attached to a hole in the lid with gaffers tape.
(this was, incidently, the only time I'd ever seen duct tape used on
an actual duct.) What you do is 1/2 fill the drum with hot water,
fill the basket with (crushed) dry ice, and fasten the lid down.
On cue, push in the handle that lowers the basket *into* the hot water
and aim the hose. 2 of these machines will fill a 20x40 stage to knee
depth in seconds, depending on room temperature and humidity.
A real *fancy* model also has a heating element
inside to heat the water (part of an electric water heater I think),
it had it's own wheels (gosh! 8^), and a fan to help out the 20 foot
hose. I love the SOUND of these machines, a nearly subsonic rumbling
(like water boiling). What comes out is fog (visible water vapor)
which is condensed out of the warm air by the lowered temperature of
the CO2 as it sublimes (I think, maybe it's also visible CO2 vapor).
In any case, it's kinda wet and quite cold and breathing it is pretty
useless, oxygen-wise. (We had this ballet once where the curtain opened
on a stage filled hip-deep in fog, with us lying hidden beneath it,
damn near passed out some nights...)
>
>The first thing which struck me was the incredible racket the machine made
>(louder than the foldback signal on our monitors, in fact), rather like
>someone driving a tractor across the stage behind us. Even a decent sized
>fan wouldn't make that much racket.
of, or they had a tractor driving across the stage behind you. (could
they have been moving the fog machine? drums full of water are heavy.)
Of course, if they were really dumb, they might have been using 30
or 40 fire extinguishers, but I can't imagine a roadie ignorant enough
not to know better than to waste money like that.
Another possibility is that they weren't using dry ice, (which drops
like a rock and disappears under spotlights) but were using one of
the many chemical smoke products.
>The other thing is that the stuff smells of perfume. I've been to
>several shows using dry ice, and it always smells the same (so it's not
>some arbitrary choice of additive). Why?
not at all like perfume. Hmm, "The Roar of the Fog Machine, the Smell
of the Fog"? memories, memories...
Bryan See
Dry ice smells damp because it is. Dry ice would only smell of perfume
if stagehands had added it. However, Rosco fog comes in several scents,
including the original scent which Geoffrey mentioned. The machines are
different for these chemicals and quite noisy.
==========================================================
= = b...@phobos.cis.ksu.edu =
= Bryan L. See = bs...@matt.ksu.ksu.edu =
= = bs...@ksuvm.ksu.edu =
==========================================================
John F Stoffel
Geoffrey> In article <14...@skye.cs.ed.ac.uk> ni...@lfcs.ed.ac.uk writes:
>Something that's been puzzling me. How exactly do these dry ice
>machines work, and what exactly is it that comes out of them?
Geoffrey> You can build one for a few bucks from easily obtainable materials.
..stuff about building one and duct tape...
Geoffrey> fill the basket with (crushed) dry ice, and fasten the lid down.
Geoffrey> On cue, push in the handle that lowers the basket *into* the hot water
Geoffrey> and aim the hose. 2 of these machines will fill a 20x40 stage to knee
Geoffrey> depth in seconds, depending on room temperature and humidity.
Geoffrey> A real *fancy* model also has a heating element
Geoffrey> inside to heat the water (part of an electric water heater I think),
Geoffrey> it had it's own wheels (gosh! 8^), and a fan to help out the 20 foot
Geoffrey> hose. I love the SOUND of these machines, a nearly subsonic rumbling
Geoffrey> (like water boiling). What comes out is fog (visible water vapor)
Geoffrey> which is condensed out of the warm air by the lowered temperature of
Geoffrey> the CO2 as it sublimes (I think, maybe it's also visible CO2 vapor).
Sorry, but the CO2 vapor is in the majority. Then Water Vapor (fog),
but not much in comparison. Just drop a chunk in a glass to see what
I mean, it's the CO2 subliming (what a neat word! :) and bubling out
of the water.
Also, you really really need to have a heater on the water. I ran one
for our production of "Macbeth" and by the fourth act, the water in
the drum was stone cold. Of course we were going through about 100
lbs. of dry ice a night per machine, with two machines. Anyway, the
heater was a 15amp draw, maybe more, and it couldn't keep up.
A better design is to have a sprinkler system spraying hot water over
the ice, sucking up the now cool water, heating it up, a spraying it
over again.
Advantages: Less water, hotter water, more CO2, no more clunking
noises as you lower the ice in and out of the water before.
Disadvantages: Need a water pump now, in addition to a fan and heating
element.
Geoffrey> In any case, it's kinda wet and quite cold and breathing it is pretty
Geoffrey> useless, oxygen-wise. (We had this ballet once where the curtain opened
Geoffrey> on a stage filled hip-deep in fog, with us lying hidden beneath it,
Geoffrey> damn near passed out some nights...)
Ah!!! The joys of oxygen deprivation! :-)
John
--
--
I dreamt about a reefer five feet long, | John Stoffel
a might immense, but not too stong, | jo...@wpi.wpi.edu
you'll be high, but not for long. |---------------------------------
when you're, a viper... <-- The Viper Drag Ain't Misbehaiving
Jeff Hildebrand
Um, I should point out from personal experience that these things can
cause some rather unexpected problems. When I was on the stage crew for Guys
and Dolls, we rented a dry-ice fog machine to use in the sewer scene. For the
first several shows we continually had problems with it, the water wasn't hot
enough, the dry ice wasn't really crushed so there wasn't enough surface area
to generate much fog, etc. Our final show was a Sunday matinee and we went all
out, putting in boiling water at intermission, making sure the ice was well
crushed and so on. Well, it worked. In fact, it worked too well. I heard the
stage manager trying to stifle a laugh and went to see what was going on. There
were clouds of fog rolling off the edge of the stage into the orchestra pit.
Needless to say, I got told to turn off the machine immediately. Sigh. We did
get one really neat effect when all the dancers jumped off a platform and
caused most of the fog to shoot out to the sides.
Then there was the problem with the fact that the person playing the
waiter in Havana decided it would be fun to put dry ice in the drink he was
serving, but that's another story...
-Jeff
Jeff Hildebrand Swarthmore College, Swarthmore PA 19081
JD...@campus.swarthmore.edu or JD...@SWARTHMR.BITNET
"Were they angels of mercy or just dance instructors?" The Bobs
"I believe in the richness and mystery of the universe and I don't believe in
the supernatural." Dan Simmons, "Phases of Gravity"
Keith R. Fieldhouse
>several shows using dry ice, and it always smells the same (so it's not
>some arbitrary choice of additive). Why?
My brother worked as the technical director at a summer stock theater in
CT the last couple of seasons (now he's a lighting designer for Ringling
Bros., he says the coffee breaks can be kind of surreal :-)) and he once
told me that they have to use scented fog so that it is not mistaken
for smoke (as caused by a fire). I don't know if that was a law or just
some strong custom/good idea but it made sense to me...
- Keith
--
Keith R. Fieldhouse k...@ral.rpi.edu
Center for Intelligent Robotic (518) 276-6758
Systems for Space Exploration (CIRSSE) CII 8313
Rensselaer Polytechnic Institute Troy, New York 12180-3590
Greg Givler - Product Assurance
>machines work, and what exactly is it that comes out of them?
>
>several shows using dry ice, and it always smells the same (so it's not
>some arbitrary choice of additive). Why?
What you have there is a Smoke Machine, not a dry ice machine,
it burns a perfumed oil and sprays that out, that is why
it makes so much noise
>
>I thought that these things just took frozen carbon dioxide (perhaps
>under pressure) and brought it up to room temperature and blasted it out.
>But, CO2 doesn't smell. Obviously, it isn't that simple. Can someone clue
>me in?
>
It doesn't smell, it also stays very close to the ground, heavier than
air you know. It also doesn't last very long under lights. It also is
tough to handle and expensive.
Greg
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Scott P Nichols
I think that you might be mistaken. As the articles before me have said, the
machine was probably a commercial fog machine rather than simply a dry ice
machine. Commercial fog machines use a commercial "fog juice" as we affection-
atley call it. It is usually alcohol-based, and comes in a multitude of
aromas...vanilla, pot-pourri, tropical, fruit punch, pina colada...
This "juice" is vaporized at it's ideal temperature so that it is not wet, but
also does not burn. The sound you hear is caused by the pressure of the fog
when it comes out the front of the machine. Yes, usually it smell great!!!
--
O- /\
|\ /\/vv\
/vv\ \ __Insight from Oregon...Scott P. Nichols
_____/ \ ~~~~~~~~~~~~~~~~ (nic...@en.ecn.purdue.edu)
Robert FERGUSON
>machines work, and what exactly is it that comes out of them?
There are two basic ways that "fog" effects are produced on stage or
in the movies: chemical fog, and dry ice. From your description, I'd
guess that what you experienced is the former: the way to tell one from
the other is that chemical fog always has some clearly artificial smell
(nausiating strawberry was always the favorite when I was doing this),
and the fact that chemical fog is lighter than air, and therefore *rises*.
Dry ice machines consist basically of a tub of water, a storage basket, an
air blower, and some hose. The dry ice is placed in the basket, the basket
is immersed in the water, CO2 "fog" is produced, and the blower sends it down
the tube to its destination. As I mentioned, dry ice fog *sinks*, and is
therefore used to get that neat ground hugging effect used in about a
million bad horror films.
The basic drawbacks to dry ice as a fog maker are that it's *EXPENSIVE*
in large quantities and you need a lot of it to make it look good. It
also disipates quickly, which can be either a plus or a minus,
depending on your application.
Chemical fog, on the other hand, can be produced about a half-dozen
different ways, and I'm afraid I can't help too much on its exact
composition. I've always presumed that it was some sort of particle
in suspension, but I honestly don't know for sure.
In contrast to dry ice, however, chemical fog typically *doesn't*
disipate, and therefore is often used at rock concerts to cloud the air
for light/laser shows and the like.
Hope this helps.
---------
Rob Ferguson ...!uunet!microsoft!robertfe
Boyd Ostroff
>The other thing is that the stuff smells of perfume. I've been to
>several shows using dry ice, and it always smells the same (so it's not
>some arbitrary choice of additive). Why?
I believe there are machines that combine both the oil-fog (smoke) and
dry-ice effect at once. The oil-fog (such as Rosco Fog) does have a
very distinctive perfumed aroma....
In article <JOHN.90N...@wpi.WPI.EDU> jo...@wpi.WPI.EDU (John F Stoffel) writes:
>Also, you really really need to have a heater on the water. I ran one
>for our production of "Macbeth" and by the fourth act, the water in
Awhile ago we got a present of steaks shipped with dry-ice at home. My
8-year old daughter was much more fond of the dry ice then the steaks!
For a quick, no-cost fog machine I found the following worked quite
nicely (fogged my 200 sq. ft. kitchen): I heated a teapot to a boil,
plugged a vacuum cleaner hose into the spout (a perfect fit!) and
dumped in dry ice. Keeping the burner on high this gave a pretty good
blast out the hose. I was actually amazed at how the water started to
freeze up even with the burner on high. It was also exciting when I
took off the lid and the CO2 fell down the sides of the kettle, smothering
the gas flame....
Kids, don't try this at your house.... :-)
== Boyd Ostroff, Tech Director == Sys Admin, "The CallBoard" ==
|||| Dept of Theatre, SUNY Oswego |||| Serving the Performing Arts ||||
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Larry Hagood
"The Wizard of Oz." When we discussed whether or not to use a dry ice fog
machine, we couldn't justify the expense. We were, however, told that by
running a "bug-juice" fogger through a heat exchanger, we could cool the
smoke enough to create ground-hugging fog similar to dry-ice fog.
Has anyone had any experience doing this? Perhaps the first poster on
this subject was smelling scented smoke that had been cooled.....
Larry Hagood Voice: (904) 644-0194
Supercomputer Computations Res. Inst. Internet: hag...@scri1.scri.fsu.edu
Tallahassee, Florida 32306 Bitnet: hag...@fsu.bitnet
Joann Zimmerman
>Dry ice machines consist basically of a tub of water, a storage basket, an
>air blower, and some hose. The dry ice is placed in the basket, the basket
>is immersed in the water, CO2 "fog" is produced, and the blower sends it down
>the tube to its destination. As I mentioned, dry ice fog *sinks*, and is
>therefore used to get that neat ground hugging effect used in about a
>million bad horror films.
In a pinch, or for very specific applications, you can get by without
the hose and blower. Steam rising from Ulrica the Fortuneteller's
stewpot in Verdi's _Ballo in Maschera_, for example ... the iron pot
sat on stage on some logs, with water and dry ice inside, fuming
away merrily. As the stuff does indeed sink, one night it did get a
little bit foggy down near ground level, where some of us junior
gypsies were camped out - so maybe the fan would have been a good idea
- although there might have been a bit of a problem with noise - never
a good idea in an opera.
"I have measured out my life with coffee spoons ..." T S Eliot
...!cs.utexas.edu!walt!jzimm
Nick Rothwell
I was apparently referring to chemical fog, rather than dry ice. I'm still curious whether the stuff is actually due to something being burned, or vapourisation of an alcohol-based substance. But anyway...
Regarding the comment that the fog/smoke is scented to avoid it smelling like a *real* fire - well, when I saw Tangerine Dream in 1980, they used this stuff, and it looked like real smoke (brown with the lights behind it), and it smelled like real smoke... Perhaps the laws are different now...
Peter Bell
I ended up in the studio of a local TV station last week, and was talking to
the effects person who was setting up and testing a fog machine. He said that
they don't use dry ice, its a special liquid, heater, and fan. The fog was
almost odourless.
The main danger with CO2 is its effect on the human (and animal) respiratory
system. Too much CO2 in the air (and its a very small amount) and your lungs
start working backwards, moving CO2 into the blood stream instead of Oxygen.
The density of CO2 also means that you have to watch out for accumulation in
orchestra pits etc. which can be very dangerous.
Peter.
usagi
>Many thanks for all the feedback on things icy and foggy.
>I was apparently referring to chemical fog, rather than dry ice. I'm still curious whether the stuff is actually due to something being burned, or vapourisation of an alcohol-based substance. But anyway...
I was told by my prof.s here (UCSB D.A. department-- Thearter Design
and Technology) that chemical fog is produced by finely misting an
oil-based substance. It's not supposed to hurt people's voices (opera
singers worry about this a lot), which I would expect real smoke to do.
Also, the laws regarding flames and stages are still very strict. I
think to be able to have a flame on stage, you need to have a
permit from the fire marshal, and have a couple of fire extinguishers
standing by in the wings.
>--
>Nick Rothwell, Laboratory for Foundations of Computer Science, Edinburgh.
> ni...@lfcs.ed.ac.uk <Atlantic Ocean>!mcsun!ukc!lfcs!nick
-Melinda Miller
Student, University of California Dramatic Arts Department.