Noobie: Doing trashcan fire and making pot smoke

[abomb10]

Ok so I'm a real noobie and I'm working on my senior project film. I have a few scenes with some pyro effects. One scene is where a guy lights a trashcan fire. I want him to drop a burning piece of paper in to the trashcan and the fire to roar up so it comes above the lip of the trashcan (but not so its dangerous). Any idea how much lighter fluid (should I use something else?) I should use to get this effect? I also want the fire to burn above the rim for about 30 minutes for the rest of the scene. I will add wood/paper to keep it going. How much should I need?

 

For the other scene, 2 cops smoke a joint in a cop car. Whats the best way to make smoke in the car? A fog machine or dry ice maybe? We're borrowing a real cop car so we don't want anything that will smell or stain.

 

The last scene is with kids lighting off firecrackers on a porch. Any advice on how to make these look good? Will they give off a lot of smoke? (thats what we want!).

 

Thanks!

[Ralph]

I would use something slightly less volatile and cheaper than lighter fluid.

 

Probably wouldn't want any pyrotechnic smoke in a cop car

 

as for getting good amounts of smoke from salutes black powder salutes give nice volumes of smoke

[scarbelly]

Just to get the fire to explode out of the trashcan, you won't need a crazy amount of lighter fluid, but you will need to spread it thoroughly around the wood and paper fire. If you aren't sure of how to make a good fire with wood and such, you should look into that because you want to be sure it will light. If you or someone you know is a boy scout, that may help if you are unsure of something. I would do a log cabin, but be sure to start off with wood that isn't too big, make sure also that any paper is separated page by page and crumpled up to give it surface area. You'd be surprised how bad people can be at making fires. You should put a hole in the trashcan to get air into the fire, or it will not likely burn as well as you want it to. Also, make sure that the top of the fire will reach out of the trash can. If it is one of those large metal trash cans, you may want to install a bottom somewhere halfway up so that the fire will be easily visible.

 

For the smoke, if it's in a moving car, definitely dry ice, otherwise it doesn't matter too much I'd think. You want it to be clear that they are "smoking" something though, so you could go out and get those fake cigarettes, or figure something else out. If it's cold where you live you might be lucky that way.

 

Are you purchasing these firecrackers or planning on making them? You say you're a real noob, so if you're making them, I'd go with black powder; anything more powerful is not a good idea for beginners. The problem with that is that you probably haven't made black powder, which will need to be pretty fast for a decent firecracker. Making decent blackpowder takes time and commitment.

Edited November 18, 2009 by scarbelly

[MilkyJoe]

I'll give you $5 to actually spark up a spliff in the cop car!

 

=D

 

Seriously though, can't see something like a fog machine or dry ice being a very good simulation for smoke from a joint. Have you asked to cops if you could smoke a cigarette in the car or is the plan to fog up the windows? If you just wanna fog the whole thing, dry ice/fog machine would probably produce a decent effect for that.

Edited November 18, 2009 by MilkyJoe

[abomb10]

Thanks guys. What else other than lighter fluid would you suggested? And how much are we talking like a cup or 6 cups? I'll definitely be careful when I stack the wood/paper so that it will burn nice. Good idea putting the bottom half way up.

 

We are smoking a "fake" joint in the car. The shot is in a parked cop car. We just want there to be a lotta smoke in the car but dont wanna smoke it out. We may or may not have access to electricity while we are shooting. Whats the best way to make dry ice smoke? Just the ice, a bowl and some distilled water? Would dry ice produce smoke that rises or that sits on the ground? How can I make it rise?

 

I'm buying the firecrackers. Hopefully it will be cold out so there's a lot of smoke that comes off..

 

Thanks again guys..

[andyboy]

With the thrashcan, just use gasoline for the first whomp, it will burn for a while. Cut. Stack a woodfire in the barrel and light it, let it burn for a while and start shooting again.

 

If you add gasoline to the wood-fire from the beginning you might get flying pieces of wood if you are unlucky. The gasoline will saturate the air in the barrel, and if you have a lot of surface area like you would when stacking a fire in the barrel it will go of like a bomb in lack of a better word. Watch this:

 

http://www.clipaday.com/videos/how-not-to-light-a-bonfire

[Swede]

I'd go with BBQ starting fluid (low volatility = safer) for the fire; for the joints, can't you have the actors smoke tobacco? Or is the idea for the car to be FILLED with smoke like a Cheech & Chong movie?

 

As for the firecrackers - I genuinely believe the easiest answer is going to be a combined effect. Use real firecrackers for the noise and effect. Somewhere hidden from the camera is perhaps a pan with a few grams of black powder. Or maybe some potassium nitrate + sucrose. The actors toss the cracker bundle into the tray, or you have it timed somehow so the tray creates the smoke safely, while the crackers do their job.

 

To make black powder crackers (small crisp bang + smoke) is not a trivial task. Usually it is a bigger boom, or a fizzle.

[Arthur]

The key is to use very little fuel and have it in a tray near the top of the bin.

 

Kerosene Gasoline or iso propanol are useable fuels 100ml could be too much. This needs to be done as a quick effect -a flame licking out of the can is all you need not a bonfire size flame.

 

Have you considered using silk flames, they look good and are a LOT safer. Don't even consider doing DIY pyro in or with a cop car you will mark yourself as a kewl faster than you think.

[Mumbles]

It really boggles my mind how you guys are suggesting he start making salutes, if even only BP. while having obviously very little experience.

 

I think you will have a hard time filling a cop car with smoke without making it smell. Dry ice is the obvious first choice, but to fill it with the visible gas would require the car be pretty cold, and probably not the smartest idea trying to use dry ice and water in an enclosed space. Additionally CO2 is heavier than air so it would sink as it came out of the windows. You might be able to get by with a big bundle of incense or something placed near a cracked window. . The cops may even appreciate the smell it would add to the car.

[abomb10]

Thanks guys. I will test out the fire before hand. I will use some BBQ fluid cause that's easy to find.

 

For the car scene they are smoking a hand rolled cigarette not real ganja : ). They probably don't want us filling the car with real smoke/incense and I told them we'd keep the windows down. The scene is with the car parked. Is it worth even trying to use dry ice to make the smoke? Or will that just be messy and look bad?

 

On another note. The star of my film is a bic lighter. Any idea how to make the flame on it bigger? And its a BIC not a cheap,clear crack lighter..haha