Measuring & Using Smoke

I've got a few scenes to do where I need atmosphere. I know the limits, problems and attributes of Rosco fog and similar devices/chemicals.

My scenes are in practical (homes) locations. Leaving the furnishings and interiors un-affected is, of course, some concern.

On a music video about 10 years ago, my crew used "cracker oil". It was beautiful. Long hang time, eleminating continuity / changes of density problems. And I loved the "look". But I was told after the shoot, that it left an oily residue all over the set -- which I can't approve of in these locations. (homeowners have been coereced into providing great locations at very low prices).

Tight spaces with union actors, so cookies are not an option.

Does anyone have thoughts, solutions to this sort of situation?

Buget is a problem, as this isn't a huge project . . .

Thanks

Jim Dollarhide

I've worked with a water based system a couple of times, I used it the second time to make sure that I wasn't imagining what happened the first time.

All the crew, who normally get on very well together, ended up screaming at each other, there's a wonderful tape of the AD and me having a hell of a fight. I didn't know that it was possible to get that many expletives into a sentence!

Same thing happened the second time I used it, haven't used it since.

Cheers

Geoff Boyle

This is going to require a leap of imagination.......but it does work.

Ever walk out of a kitchen with bread stuck in a toaster.....cooking away, and how are you reminded...smoke everywhere...great hang time...great dispersion...impossible to get rid of...and it's people friendly...plus there is a good chance the homeowner has burned a few in their day and they will probably be fine with it.

I kid you not. White bread works best.

Glenn Suprenard Dir/DP Matinee Pictures

Silent water-based Hydrosonic Hazer at about $250 @ day.

Probably the very same type that caused Geoff to throttle the AD.

Available at Towards 2000 (I think they're still around). Tel: 818.557.0903 in Burbank.

Also try TMB Assoc. Tel: 818.842.9652 in Burbank

Can you put away the heirlooms and re-dress the place a bit and use the Cracker Oil? The oil does clean away OK.

Mark Doering-Powell

Some problems here--actually water-based smoke is MORE harmful than oil-based cracker types, as it relies on inorganic complex molecules to bind the smoke to water droplets. Yes, there is less residue, but breathing it is more harmful. Cracked-oil foggers at least have the advantage of being "organic."

Liquid nitrogen, at least as I have used it (just last week) produces a thick, extremely kinetic, volume of cumulus cloud-like smoke--not the type of atmospheric effect one usually prefers on the set.

Chris Taylor

Do you think it's possible that the frequency that the Hazer operates at stimulates the brain in such a way as to cause tension / anxiety / fights on the set. I seem to recall the army experimenting with frequencies that could cause anything from dissorientation to... bowel activity.

Not to start a thread here but... who knows what lurkes out there - even on our own set.

Ari (they're watching... I know they are) Haberberg

There is a product called "diffusion in a can" - it may (or may not) be a Rosco product but as I recall, it doesn't leave any residue on location and it has a fair hang time, though not quite as long as oil cracked fog. I haven't used it in about 8 years so I might be imagining the results - anyone else have any notes here?

Ari Haberberg DoP, New York

>Liquid nitrogen, at least as I have used it (just last week) produces a thick, extremely >kinetic, volume of cumulus cloud-like smoke-- not the type of atmospheric effect one >usually prefers on the set.

I'm sorry that I've missed the first portion of this discussion. If you're looking for safe, fog effects - glycol based products are your best bet - Roscofog, Gamfog, et al. However, if your dealing with water smoke effects - you're creating a natural fog. Fog can be created by forcing water at a very high pressure (usually over 1000 psi) through a tiny nozzle with a sharp rod in it that breaks the droplets of water into tiny sizes. The water then hangs in the air -- just as natural fog does. There is nothing unnatural or hazardous about this system whatsoever, with the sole exception that it will get surfaces wet and slippery. You can create a fog effect from a humidifier -- and there certainly is nothing unhealthy about that...

Another distinction to be made is the difference between smoke and fog. Smoke is a combustion process in which one element is chemically changed into another through a process of combustion. Fog is composed of liquid droplets suspended in the air and can be produced by a variety of processes - but not burning.

Cracked-oil foggers use a method of "cracking" mineral oil into tiny droplets (10 to 20 microns in diameter) to be sprayed through a high pressure nozzle into the air. The health hazards of a cracked oil system depend greatly on the grade of the mineral oil. However, this system does reduce the size of the oil to a vapor, which when respirated is small enough to pass through the lining of the lungs and into the blood system. ANY vapor can be harmful. These buggers are not kind to our bodies.

Glycol based systems, also called water based systems, use a combination of a glycol and water through superheated nozzle to hand glycol particulates in the air. An intensive study was done of glycol (a very popular benign substance in everything from shampoos to Twinkies) by The Cohen Group and they determined that there is absolutely no health hazards to prolonged exposure. (Prolonged based on reviewing several Broadway shows over a specified period of time that the performers were exposed... Can't find the details right now - but if you're interested e-mail me.) They determined that there were no health hazards connected to glycol fogs. Some people had cases of eye and throat irritations, but that was found to be a specific allergic reaction as opposed to a common hazard.

If anyone is interested - I have copies of the NIOSH findings of this study as well as a copy of the US Army Biomedical Research report on oil based fogs... I'll snail mail copies to you if you e-mail me a request.

All of this information is available through either ESTA 212-244-1505 (Introduction to modern atmospheric effects 2nd edition) or through the Cohen Group 650-349-9737.

Of course the remaining fog type is cryogenic like dry ice and liquid nitrogen. The hazards here are a condensation layer that can be slipped on and depletion of oxygen. The fog that won the Academy Award in 1998 was called Liquid Synthetic Air and was a combination of liquid nitrogen and oxygen that was 100% breathable and benign...

Too much info?

Hope that answered the original question.

Jay Holben

Wow! Thanks, Jay. Great information.

Feliciano di Giorgio

Nick Patton wrote :

"There is a unit called a DF50..."

That's my fogger of choice when I want to see xenon beams, streaming sunlight, or a smoky bar scene. In other words, a hazy atmosphere. I haven't noticed the crew fighting any more than we usually do...

Norman Bonney

This tip came down to me from the gaffer I used to work with when I was shooting promos (I think he was told by Douglas Slocombe!). Stick a parcan in a corner, pick a spot on the other side of the set, take a reading with your spot...Perhaps not as accurate as AP's but then you don't need to buy a meter that takes "shields".

Regards,

Shangara Singh

Measure the smoke by picking a spot in a dark (black) portion of the set. Use a spot meter and measure that same spot from the same position for a constant smoke level. The easier way is to train your eye to evaluate the smoke level in the same manner.

Roy H. Wagner ASC

Of the many ways to "measure" smoke in a room it would probably be less time consuming and comparably effective to "measure" the density of the smoke by eye, take a spot reading of the smoke itself, and just be consistent with your exposure. There will be times where you will want the smoke lighter than you have had it for certain shots; so your exposure will become more important in that instance. Smoke is one of those effects that is always going to be somewhat inconsistent but if you use good eyes and approximations the inconsistencys will not read on the film.

Thomas Osaze DP - ATL/LA

In the mentioning of measuring smoke, (I use a gray card, an inky, and a spotmeter far away on a stand) no one pointed out to have the smoke generating device far away from the meter jig. I like two or three generators pointing at the opposing walls.

In model work it is imperative that the level stay the same throughout the course of a 4+ hour Motion Control shot. There are a couple of proprietary atmospheric level control devices that I have never used but I am all for automation when appropriate. In production I'd think it's best to develop an eye for the effect in a particular shot just like you do for everything else.

Eric Swenson

All the means of measuring smoke with various meter readings make a lot of sense. In aviation, during bad weather they evaluate Runway Visual Range (RVR) with a device called a transmissometer (don't laugh I looked it up, check for yourself at : http://www.tc.gc.ca/aviation/regserv/term/gpatsphtml/t.htm ) which is basically a known amount of light a and a pick up device that measures the light some distance away. By knowing the light loss they can estimate the anticipated visibility in the runway environment. Should work for smoke in a room. Works for helping land aircraft's worth millions in crappy visibility with hundreds of people in them.

Daniel Villeneuve, c.s.c.

Someone does make such a device that I've seen on a commercial with motion control. I was shooting live elements for the commercial and wasn't involved in the smoked set. But the device is definitely available and I recall it coming from LA.

Looking back in my CML files, I see a post from Mark W. that suggests Guy Marsden in Oakland, CA. Guy's number is 510 536-1472 phone and 510 536-1435 FAX.

Mark's post suggests that Guy builds these but perhaps he knows of available rentals.

Jim Sofranko

I've used a couple of different *automatic* hazers and smokers but they seem to make too much noise when left alone. Turning them off and on (between takes) causes the same problems as with a manual system: delays and varying levels.

The best way to get consistent smoke is to have a good machine operator. I meter something neutral that won't change (lighting) from across the space (mark it) and use that to trim what I sense by eye, but a good operator will make that conversation a lot less frequent.

Is it just me, or are crews, in general, more quick to complain about smoke and it's use *in the work place*? Of course, I respect the health and safety of the crew, it just seems I don't get to use smoke much anymore - often shut down in production meetings with crew complaint as the reason.

I know it's a controversial issue, BUT I like the oil based smoke WAY more. It looks better, hangs for the whole take, and is easier to use in filling large spaces. For me, the *safe* smoke (the Rosco stuff that is *approved*) looks gassy/thin, does NOT hang well, smells funny and gives me a sore throat.

Who wants to breathe some weird, pocket protector, version of green apples all day? That stuff is GROSS.

David Perrault