Smoke Bomb Question

[cosmarchy]

Hi,

 

I'm trying to create a reliable smoke bomb and am wondering whether anyone can tell me what I can so to reduce reduce the burn time and prevent the large flame which it produces...

 

I have a mixture ratio of 3x potassium nitrate to 2x sugar. I've tried with the ingredients coarse and with finely ground. I've tried them mixed with water and without.

 

The issue is that all hell breaks loose when I manage to get them going. By that, I mean fire and brimstone where there is a foot high flame spewing out all manner of projectile as well as smoke. This only goes on for about 10 seconds before burning out. Hardly very long at all.

 

What can I do deal with the flame? All the tutorials I've seen with the same ingredients don't have this flame, so what am I doing wrong?

 

I've also seen the tutorials where it is lit with a visco fuse but mine just fizzles out before the mixture is ignited...

 

Thanks

[Arthur]

Almost all of the art of smokes is getting the burn restricted enough to make sure it burns only with the oxidiser. Smoke pots are usually lit inside the case. Otherwise the flame uses the oxygen from the air and doesn't smoke.

 

You can also try to slow the burn by adding inerts (woodmeal, sawdust etc) or flame retardants (like carbonates or bicarbonates).

[davidh]

Put a tiny amount of granulated green BP as the start of the first increment in your device. This will act as a prime and get it going. Often the trick is use a small amount of weak BP, maybe even something like Chrysanthemum 6 star comp. Too much and it might pop.

 

Add more sugar to the ratio until it slows down. I've never been much of a fan of KNO3 + sugar for smoke. I like sulfur based smoke for cheap and simple smoke bombs.

[Arthur]

The reason that lactose is sometimes used as a fuel is that it burns with a cool flame. All smokes rely on incomplete combustion and this requires keeping the comp and the flame inside the device and keeping the rate down so that the case isn't ruptured.

 

http://www.thegreenman.me.uk/

 

Getting the case right and getting the comp right are probably equal parts of the problem.

[davidh]

The reason that lactose is sometimes used as a fuel is that it burns with a cool flame. All smokes rely on incomplete combustion and this requires keeping the comp and the flame inside the device and keeping the rate down so that the case isn't ruptured.

 

http://www.thegreenman.me.uk/

 

Getting the case right and getting the comp right are probably equal parts of the problem.

Wrong. Pyrotechnic smoke is either a sublimated colorant/dye in the case of sulfur or combustion products in the case of KNO3+sugar.

Edited September 13, 2021 by davidh

[Arthur]

Ignoring coloured smokes, most others are partial combustion products. Naphthalene/Anthracene smokes are simply the product of just the hydrogens from the aromatic compounds burning and the micro particulate carbon being the smoke. It's the case that divides the burning by oxidant phase and the burning to completion in air phase

[cosmarchy]

Thanks for your advice guys

 

I'll have an experiment at the week end when it's a bit lighter outside.

 

@davidh - when you suggest a sulfur base, would you be thinking along the lines of KNO3 / Charcoal / Sulfur in a 4 / 5 / 10 ratio?

I'll also try adding a bit more sugar and see how I get on there too.

 

@Arthur - I have some bicarbonate of soda, so I'll try and add some to see if I can get the burn rate down.

I have some lactose too so I could also try this. Would you be thinking of a straight swap with the sugar or just some of the sugar?

[Mumbles]

I don't know of much work in the way of potassium nitrate smokes using lactose. Lactose is mostly used in colored smokes with dyes, which as David mentioned function differently. Worth a shot if you'd like, but I wouldn't expect it to be a cure-all.

 

To be honest, I don't really know exactly how nitrate/sugar smokes work. The smoke, whatever it is, is flammable. If it gets too hot or too much oxygen it ignites, burns, and makes a pretty weak resulting smoke in the end. That makes me think it's not just potassium oxide or carbonate or some inorganic salt. I'd think it'd have to be some sort of partially burned sugar or organic in the smoke.

 

Carbonates are often effective at slowing the burn a bit and helping to reduce it from flaring up. The added carbon dioxide in the flame probably help it from flaring up too. More sugar probably would also help. My favorite carbonate is magnesium carbonate, but it's not particularly over the counter. Sodium bicarbonate will work in a pinch.

[FlaMtnBkr]

If you can make the exit longer to allow the smoke to cool it helps prevent it flaring up and burning the smoke, which is basically atomized fuel. In fact engines can be converted to run on smoke from an oxygen starved wood fire. It wants to burn with oxygen so you have to reduce the heat to prevent the flame. That or reduce the oxygen or oxidizer, but once it reaches air this is not easily controlled. I've also had success turning a flaming smoke upside down on the ground to smother the flame and it immediately starts smoking.

 

My suggestion would be to use a formula that adds wax to your mix. Melting and vaporizing the wax requires energy or heat and helps cool the burn, and the vaporized wax contributes a great amount of smoke. I can find a formula but will have to go thru my notebooks, though a search of legendary smoke mix should provide a good start (I think it's 40/40/60 wax, sugar, kno3).

 

If it doesn't want to burn but makes (what sounds like) a sputtering but somewhat fierce burn, I would say it needs to be more finely ground and better mixed. I would also suggest some oil instead of water to try to tame it. Smoke is tricky and many times small adjustments need to be made with a different batch or particle size of chemicals.

 

Another curious and quick smoke is to mix ammonium nitrate into water until no more dissolves. Then soak sheets of newspaper in the solution and lay in the sun to dry. Once dry roll a few sheets into a tight cylinder and wrap in aluminum foil and run a fuse into the center. Once lit smoke starts coming out and really starts pouring out once it gets going and I never had a problem with flame. The only problem is the ammonium nitrate is deliquescent (sp) and quickly absorbs enough water to ruin it. Though I've since found that if packaged and placed in the freezer, ammonium nitrate doesn't gain much if any water. I have no idea why it works so well and produces so much more smoke than smoldering newspaper alone. My best guess is there is some type of chloride used to produce newspaper and it forms a fair amount of ammonium chloride, but that's just a wild guess.

[countryboy7978]

On 9/12/2021 at 9:11 PM, davidh said:

Put a tiny amount of granulated green BP as the start of the first increment in your device. This will act as a prime and get it going. Often the trick is use a small amount of weak BP, maybe even something like Chrysanthemum 6 star comp. Too much and it might pop.

 

Add more sugar to the ratio until it slows down. I've never been much of a fan of KNO3 + sugar for smoke. I like sulfur based smoke for cheap and simple smoke bombs.

Sorry for digging this up but didn't want to start a new one. You mentioned a sulfur smoke formula. Do you mind sharing what your ratios are for small consumer sized white smoke devices? 

[SharkWhisperer]

59 minutes ago, countryboy7978 said:

Sorry for digging this up but didn't want to start a new one. You mentioned a sulfur smoke formula. Do you mind sharing what your ratios are for small consumer sized white smoke devices? 

If you want to gag yourself and anybody in the vicinity, please proceed with S-based smoke bombs.

Here's a link to a common smoke bomb for killing rats in their holes: https://www.walmart.com/ip/Atlas-Giant-Destroyer-Gas-Bomb-Gopher-Mole-and-Rat-Killer-Pack-of-1-4-count/38472647?from=/search

Smouldering underoxidized comp of 50% NaNO3, 38% S, 9% charcoal, and 3% other junk.  Nice thick cloud of SO2 to acidify your eyeballs and respiratory passages! Amdro Gopher Gassers use 45% KNO3 + 45% S + 8%C + 2% binder/junk...

For making smoke about the only thing sulfur has in its favor is that it's cheap. And great at killing gophers!

[countryboy7978]

Commercial Class C/1.4 smoke bombs (white not color) are most certainly sulfur based. The smoke is very white and acrid. Based on CPSC and APA guidelines for consumer fireworks (I'll have to find the link) KNO3 and Sulfur are the approved chemical components for white consumer smoke. I have opened one of the old Ozark Smoke tubes and the powder is off white in color with a strong smell of sulfur. 
 

Unfortunately Tom Scaman from Apollo of the Ozarks passed away last year and I never got a chance to ask him what composition he used. 

 

Here's the link: 

https://www.americanpyro.com/assets/docs/PHMSADocs/apa stand 87-01.pdf

 

page 8, section 3.2.3 for Toy Smoke Devices. 

Edited February 20 by countryboy7978

[davidh]

The smoke from a sulfur based smoke bomb is from fine sulfur particles, not SO2. There should be little SO2 if they are burning correctly. If they burn incorrectly, they make a ton of SO2 and little to no smoke. It mostly has to do with dialing in the nozzle size.

Degn White Smoke from Novelty Fireworks (L-107) is 12 parts KNO3, 16 parts flour sulfur, and 1 part airfloat charcoal. Just screen to mix. The components are cheap so they are good to experiment with. Ram in a tube with clay ends, drill a nozzle like you would for a gerb, put a touch of prime in the hole, and fuse. 

[countryboy7978]

10 hours ago, davidh said:

The smoke from a sulfur based smoke bomb is from fine sulfur particles, not SO2. There should be little SO2 if they are burning correctly. If they burn incorrectly, they make a ton of SO2 and little to no smoke. It mostly has to do with dialing in the nozzle size.

Degn White Smoke from Novelty Fireworks (L-107) is 12 parts KNO3, 16 parts flour sulfur, and 1 part airfloat charcoal. Just screen to mix. The components are cheap so they are good to experiment with. Ram in a tube with clay ends, drill a nozzle like you would for a gerb, put a touch of prime in the hole, and fuse. 

Thank you. I will try to run that mixture and see how it goes. 

[PyroGb]

Ok so I’ve spent a good deal of time on this subject and this is what I’ve gotten to work. First you take a small can with a sealable lid and pepper the outside with half to quarter inch holes, then you prepare the mix it is 72 grams  kno3 36 grams sugar 20 grams paraffin this can be scaled. First you melt the paraffin and slowly ad the oxi/sugar in until you have a grey paste. Scoop this into your container and put a fuse in. If lighting insurance I and some kno3 sugar on top where the fuse is. The paraffin slows the reaction down and doesn’t burn completely away so it gets emited as thick smoke. If you want I can show a vid but it consistently burns for 3.30 to 4 min 

[countryboy7978]

On 3/2/2024 at 10:43 AM, PyroGb said:

Ok so I’ve spent a good deal of time on this subject and this is what I’ve gotten to work. First you take a small can with a sealable lid and pepper the outside with half to quarter inch holes, then you prepare the mix it is 72 grams  kno3 36 grams sugar 20 grams paraffin this can be scaled. First you melt the paraffin and slowly ad the oxi/sugar in until you have a grey paste. Scoop this into your container and put a fuse in. If lighting insurance I and some kno3 sugar on top where the fuse is. The paraffin slows the reaction down and doesn’t burn completely away so it gets emited as thick smoke. If you want I can show a vid but it consistently burns for 3.30 to 4 min 

Thanks. Maybe someday I'll try this. Right now I'm trying for a very specific vintage style from the DOT era. 

[PyroGb]

Cool and good luck

[countryboy7978]

Just a follow up: KNO3/Sulfur/Powdered Sugar worked exactly like the old Class C item. 
 

5/4/1