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Old February 26th, 2006, 11:46 AM   #1
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theatrical Smoke VS. Theatrical Fog?????

Is there a difference... or just generic terms. I've read where "adding some particle to the air" can help with the film look. What I'm not sure about is the Halloween seasonal foggers. When talking about these machines for theatrical (Smoke/Fog), are the two terms used interchangabley and generically or is there a difference. I'm wondering if they are definitely two different machines for each phenomenon (one for fog and a different one for smoke). And if so, what are the airborne dynamic properties of each (which one stays suspended and visible for the longest).
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Old February 26th, 2006, 01:50 PM   #2
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Theatrical fog tends to be generated by solid CO2, aka "Dry ice", in water. It is not terribly long lasting, and hugs the ground. It will not give you the particulate effect you are looking for.

Theatrical smoke, also known as haze, is closer to what you are looking for. It has a longer "Hang" time than fog, and a much more even dispersion throughout the air. How long the hang time is depends on the movement of air in your room.
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Old February 26th, 2006, 06:48 PM   #3
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Michael is more or less right.... if you want to get technical. However the terms "smoke" and "fog" are used pretty interchangeably. So you have to know a few more specifics about the process.

Setting aside CO2 effects, there are three popular technologies used for fog/smoke/haze. One of them uses a glycol based fluid (glycol is also used in antifreeze) blended with varying amounts of water depending on the manufacturer and intended purpose of the effect.

Then there are mineral oil based machines which generate "haze." Haze - as opposed to fog or smoke - is an effect where the particles disperse evenly throughout the space and "hang" in the air for a long time. This is typically the effect you'd use to make light beams visible, for example.

The third type of machine uses glycerol (an edible substance) suspended in water. These are also used for "haze" effects and typically contain 80% to 90% water.

Each type of machine is designed for a specific effect with a specific type of fluid - you can't just randomly use a different brand of fluid from another company.

You should be aware that the use of these effects is a very contentious topic among the various unions in film/video/theatre/opera. There are very real concerns about the safety of inhaling these substances over long periods of time.

But to get back to your original question, machines and fluids from major manufacturers have been tested and results of exposure to them are generally a know quantity. Using a cheap fogger might be a concern for anything more than very brief casual exposure. Caveat Emptor...

Before using any effect like this you might want to read the following study: http://www.shape.bc.ca/resources/pdf/summary.pdf
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Old February 26th, 2006, 07:55 PM   #4
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Thanks Boyd. I think you just talked me out of it all together. I am going to be shooting with my 4yr old daughter and if there are any questions at all about hazards with these effects, I will not do it. I want to do a B&W Noir Short that looks like it was made in the 30s and thought that some "particle" in the air would help authenticate the look but I guess its just too bad now. Oh well. Safety first. Thanks again.
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Old February 26th, 2006, 08:22 PM   #5
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I wouldn't worry an awful lot about short periods of exposure personally. But if you're concerned, you could go to a theatrical supplier and rent one of the better hazers. My personal favorite is the MDG "Atmosphere." It uses tiny amounts of mineral oil to produce a fog that hangs in the air for hours. In a smaller space it would only take a minute or two of operation to give a nice effect. The CITC DF-50 also uses mineral oil and is very effective - possibly cheaper to rent. The downside is that it's very noisy, but you could shut if off as soon as the haze effect is established.

Here at the opera company, the LeMaitre G300 is the only machine which our performers union has approved. It uses a glycerol fluid consisting of 80% water. This isn't really an endorsement of their technology, but it's just the machine which we got the membership to approve four years ago. I'd like to get approval for the MDG Atmosphere when we renew our AGMA contract this summer, but the whole haze issue is such a hot button it may be better for us to just leave well enough alone...
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Old February 26th, 2006, 09:18 PM   #6
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I wonder what kind of effect that stuff has on furniture and carpet. I will be shooting at home. I have a family room with a 17.5ft ceiling. That is where I will shoot. But with 80% water, it shouldn't have no more of an affect on my furniture & carpet than a humidifier would. Do you know if there is any kind of an oder/smell residue left behind with these effects? Thanks again Boyd.
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Old February 26th, 2006, 09:47 PM   #7
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I think you'd be fine if you only ran the machine for a short while. There shouldn't be an odor from mineral oil, it's inert and non toxic. The concerns revolve around what happens when those microscopic particles are sucked into your lungs. But as I said, in a space that small you'd only need to run the machine for a few minutes. In a 3,000 seat theatre we can create a beautiful haze by running the MDG Atmosphere or CITC DF-50 for perhaps 15 minutes, and that's in a space of perhaps 60,000 cubic feet. We used the MDG for a PBS broadcast that was shot at the Mann Center in Philadelphia a few years ago. This is a venue with an enclosed stage and open-air audience. To my amazement, the machine was hazing the outdoor amphitheatre as well as the enclosed stage! But running a machine like that continuously probably only uses a couple ounces of mineral oil during a period of a hours (Johnson's Baby Oil = mineral oil). OTOH, I've read about film/video shoots which ran all day in a small studio while the hazer was running constantly. Everything was coated with an oily film afterwards. The bottom line is probably just using some common sense. Check with a local theatrical supplier. I'm sure the daily rental rate on these machines is very modest, and you can learn by trying.

"Rosco Fog," which is a glycol-based fluid, used to come in different "flavors." I haven't used it in years since the singers' union doesn't allow it, so not sure if they still make the different scents. Urban legend has it that one of the original varieties was called "pot" :-)
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Old February 27th, 2006, 08:21 AM   #8
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The inexpensive DJ-type "fog" machines really do make something akin to fog. They use a glycol and water solution and heat it up in a small chamber. It doesn't seem to leave any residue. The Glycol used is primarily Propolene Glycol, which is also used as a food additive. It is MUCH less dangerous than anti-freeze. Actually, it is used in "eco-friendly" anti-freeze due to it being non-toxic. It can also be run through a cooler filled with ice to make it cold enough to hug the ground. Just look up Halloween fog and there are lots of tutorials and ideas. Obviously, if someone shows allergic reactions to anything, remove them from the source and seek medical attention. Personally, this stuff can in no way be as dangerous as cigarette smoke.
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Old February 27th, 2006, 09:22 AM   #9
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Quote:
Originally Posted by Marcus Marchesseault
The Glycol used is primarily Propolene Glycol, which is also used as a food additive. It is MUCH less dangerous than anti-freeze
Mineral oil and glycerol are also non-toxic. But that is pretty irrelevant actually, since the health concerns are related to tiny particles entering the inner passages in your lungs. It's a respiratory issue which is not related to ingesting the fluid. I would really encourage everyone to read the PDF file in my link above. As I said, occasional exposure for short periods of time is not much cause for concern. But if you work regularly in the entertainment industry you should familiarize yourself with this issue. You could have some liability if you're in charge of a project using fog/haze and a cast or crew member complains about health effects. Does this mean you shouldn't use fog? Absolutely not! But just educate yourself a little on the issue so you can make informed decisions.

The conclusion of that report is a bit worrisome

Quote:
Compared to the control group, the entertainment industry employees had lower average lung function test results and they reported more chronic respiratory symptoms: nasal symptoms, cough, phlegm, wheezing, chest tightness, shortness of breath on exertion, and current asthma symptoms, even after taking other factors into account such as age, smoking, and other lung diseases and allergic conditions. The entertainment industry employees also had increased rates of work-related phlegm, wheezing, chest tightness, and nasal symptoms. Most of these symptoms and decreased lung function were associated with having been exposed to greater amounts of theatrical smoke and fog (higher levels and more days of exposure) over the previous two years.
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Old February 27th, 2006, 10:21 PM   #10
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"...since the health concerns are related to tiny particles entering the inner passages in your lungs."

The glycol is not burned in the heating chamber, so it is a mist that develops, not particles. The glycol (miniscule amounts) is probably absorbed by the body through the lungs and shouldn't get stuck as particles. There are much worse things you can put in your lungs, like city air (vehicle exhaust), indoor air (evaporating manufacturing chemicals in furnishings), and cigarette smoke. Sawdust, and especially concrete/tile/stone dust are much worse for you than glycol since they are inert and won't get processed out by the body.

Personally, I won't use the mineral oil fogs, but I also am a smoker-hater. I also wear protection when doing work with hazardous materials. Glycol isn't pure air, but it won't suffocate you or clog your lungs. It is something to be minimized, but it is pretty far down the list of things we should be avoiding. The cigarette smoke in a night club is far more dangerous than the fog machine.

You know, we should start a thread on health issues for videographers. I know I would like to hear about health problems relating to this field. I'll bet bad knees is high on the list.

Oh, I forgot to say that I did read the report. It really seems to say that the mineral-oil is bad and one should not breath solid glycol smoke all day. This shouldn't be a problem for people only using it on odd occaisions. Still, keep your mouth off the fog outlet nozzle!
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Old March 1st, 2006, 09:26 AM   #11
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Quote:
Originally Posted by Steve Witt
I wonder what kind of effect that stuff has on furniture and carpet. I will be shooting at home. I have a family room with a 17.5ft ceiling. That is where I will shoot. But with 80% water, it shouldn't have no more of an affect on my furniture & carpet than a humidifier would. Do you know if there is any kind of an oder/smell residue left behind with these effects? Thanks again Boyd.
I recently used a Rosco fog machine in an apartment with tall ceilings (15ft). The location owner complained about a slight smell for a couple days afterwards. There wasn't any discernable residue - though there had to be because my clothes stank!

Coincidentally, the film also featured a 4yo girl. She didn't like the smell and complained of some throat scratchiness. And she wasn't being difficult - she was a trooper for the rest of the shoot. We worked about 6 hours in moderately heavy fog and most crew members did have some respiratory symptoms. Nothing serious, but something to consider.

BTW, the director ended up leaving the shot on the cutting room floor because it didn't work. The shot was fantastic - it's in my reel but the motivation/performance/etc wasn't there and we're reshooting a completely different shot later this week.
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Old March 1st, 2006, 09:53 PM   #12
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What sort of machine was it? Did it use water/glycol or mineral oil? It is impossbile to have a smoke smell with glycol. I can "feel" fog, but not smell it. It is like being in a shower with steam although it doesn't condense on surfaces that I can tell. Are you sure you weren't using a mineral-oil based "haze" machine?
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Old March 2nd, 2006, 07:54 AM   #13
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Glycol fog will not have a smoke smell, but it does have a detectable scent. In fact I believe rosco used to have specially scented fluids such as citrus etc... to mask the "fog" smell.
For the original posters desired "film noir" look, and to address his health and safety issues, I would without hesitation recomend the DF-50 hazer made by reelfx. The DF-50 is the standard hazer in live production. (from the Grammys, to the Rolling Stones, and almost everything in between. It has been tested by Cal-OSHA. Their results can be found here:
http://www.reelefx.com/products/calosha.htm

It has been approved by Actors Equity, and The League of American Theaters.
The MSDS can be found here:
http://www.reelefx.com/Documents/MSDS%202004.doc

I do not work for ReelFX, or any of their distrubitors. However I have used their machines on almost every show I have done since 1994.

The machines are noisy, but the haze usually hangs for a long time. So run it until you have the look you want. Turn it off when you are ready to shoot.

They can be found at most major live production lighting companies. Your post indicates you are in KY. I know PRG (www.prg.com) and Bandit Lites (www.banditlites.com) both in Nashville, TN carry DF-50's.

Hope this helps, and good luck

Ronald Beal
Lighting Designer, Director, Programmer, Operator, Crewchief, Technician, Gaffer.
Television and Rock & Roll
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Old March 2nd, 2006, 08:15 AM   #14
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Quote:
Originally Posted by Marcus Marchesseault
I can "feel" fog, but not smell it.
Well you're certainly the exception in that case. There is definitely an odor to both the glycol and glyerol fogs/hazes. The smell of the oil based haze is less noticeable.
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Old March 2nd, 2006, 08:22 AM   #15
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Originally Posted by Ronald Beal
The machines are noisy, but the haze usually hangs for a long time. So run it until you have the look you want. Turn it off when you are ready to shoot.
Take a look at the MDG Atmosphere hazer. I see them replacing the DF-50 quite a bit. They're terrific machines - almost completely silent. They use mineral oil like the DF-50, but have a tank of compressed gas (CO2?) instead of the noisy pump in the DF-50. They're much more expensive however. http://www.mdgfog.com/pdf/atmosphere-aps-series_e.pdf
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