15 replies to this topic

[blackplasma]

ive just got back from testing 3 smokes in the woods and i could do with some advise on how to improve them please?

1# 100g 40/60 powdered lumpwood charcoal / powdered KNO3 PLUGGED WITH A LITTLE SUGAR/KNO3
2# 100g 40/60 caster sugar / KNO3 COOKED
3# 100g 50/50 caster sugar / KNO3 COOKED

1# burned for ages and hot with about 8 inch flame and gave off a fairly dense cloud
but... popped the plug out which burned on the floor and the flame was a safety issue

2# burned for quite a while with a 6 inch flame and the cloud was very dense
but... the flame would still be an issue

3# burned for the longest with no visible flame and gave a weak cloud
but... the cloud was not dense enough to move behind

the best result was #2 as #1 is a powder and therefor not really suitable for storing in my pocket whilst im running round a wood all day, and #3 didnt produce enough smoke
but the problem is the flame,. it isnt safe to have a naked 6 inch flame in the woods.

the advise ineed is?!

how can i reduce the flame size of the #2 or could i conceal it with an extended tube?
could i add a non reacting packer like plaster powder or brick dust or something to absorb some of the heat?
could i alter the tube dimentions to get safer results?
could i adda nything else to the mix to help?

or would i be best off trying a 45/55 mix

[Pretty green flames]

Try adding about 10% parrafin wax to it. Based on other people's experience this reduces flame output and somewhat increases smoke output. Might be worth a shot.

[minalth]

The smoke is produced by incomplete combustion (i think)
Maybe choke the mix so it reduces the oxygen that can get in from the air. That way you control it with the proportion of kno3.
Then put the tube inside a tin can inside a larger tin can

-----------------------------------I
I----------------------------- I
I I
I ----------------------I I
I xxxxxxxxxxxxxxxxI I
I xxxxxxxxxxxxxxxxI I
==============================

very bad picture but mirror it along the = line to get a cross-section, im too lazy to draw the rest.
The X is the composition.

If that didnt make sense, imagine rotating it around the line of === in 3D.


not sure it will work but might offer some protection and I just have a gut feeling that it will also increase smoke production...


EDIT ok, the ASCII picture doesnt work, the sizes change or something. Just imagine the tube full of comp, then put it burn end first into a coke can with the openable end removed, and somehow make it hang in the middle. Then put that open end first into a tin can and suspend it.

Maybe have some visco going all the way in, or quick match once it gets a certain distance...

careful of the plastic smoke from tin cans...
Then put that

Edited by minalth, 11 March 2007 - 02:59 PM.

[cooperman435]

Your problem is sustaining a hot enough flame to produce the smoke but reducing its size.

I would suggest testing a few ratios of sugar/kno3 from 20/80 to 45/55 to establish the best smoke producing ratio then just get a reasonably thick walled tube I get mine from a shop that sells sewing suplies its what the material rolls come on and I get them for free.

if your wanting say a minutes worth of smoke charge the comp into a peice of 100mm tube an burn it with a timer to establish its burn rate then multiply or divide this to get a minutes worth of burn

Ie if it takes 30 seconds for it to burn 100mm then your gonna need 200mm of comp.

DONT choke it or use a plug as this will increase the burn rate and the flame length and invites catos of the device.

To reduce or get rid of the flame when you are timing the 100mm peice also check how long the flame comes rises up from the top of the tube and when you make the end product cut this much extra with your tube and charge the long tube with your 1minutes worth of comp and ignite the end inside the tube so the flame never makes it out the end.

This is a good method of making them but I usually have about only 10 to 20 seconds of smoke comp in mine or te tube cannot take the heat and begins to burn.

[adamw]

The flame is caused by the volatiles that make up your smoke combusting.... and you don't want that because you will loose a lot of the smoke. Ideally you want it to 'smoulder'. You can achieve this with a succession of 'baffles' that stop the flame developing and allow the gasses exiting in the smoke to cool below combustion temperature. Here is diagram:

[Ritual33]

Nice idea, how would you construct this adam? What would the "baffles" be made from?

Cheers,
Drew

[cooperman435]

Adam wouldnt my longer tube idea do the same?

I simply use a tube 3 times longer than the composition and ignite the end inside the tube so the unburnt volatiles cool enough before they leave the tube not to ignite.

[Asteroid]

I have found 27:40:48 paraffin wax:sugar:kno3 and a pinch of Bicarbonate of soda/100g to be highly effective. It can be lit, thrown and left, there is little or no likelyhood of flame production, the smoke is as thick as a commercial chlorate grenade, its solid, will still light if it's been rained on, but probably cant take soaking, and is a nice solid. Baffles would be a good idea for extra security, since the smoke is flammable, and It has ignite when I've used other ratios. Also the smoke is a litte coughy if you take a deep breath of dense smoke, and if the mix isn't powdered well, it will produce a cylinder of dross to pop out 3/4 way through, which is hot

[Creepin_pyro]

Nice idea, how would you construct this adam? What would the "baffles" be made from?

Cheers,
Drew

You can see some baffles here:

http://www.firefox-f...es/dscn2163.jpg

Most commercial smokes I've seen (and the ones in the above kit) only use a single disc which seems to work well.

[blackplasma]

ok, so a few people mentioned parafin wax so i just tried it, i used 40g sugar and 60 g KNO3 again and added 10 g of ground up candle, (i was told standard candle wax IS parafin wax but correct me if i am wrong) but.... i just wanted to check that i am still meant to cook up the mixture beccause it seemed to seperate in the pan and altho the wax made the mix flow like a dream and not stick all over the place i am not sure if much of it 'soaked'in to the mix i would say that maybe a quarter to half of it had to be poured off the top as i didnt want it to just take up space at the bottom of my tube.
i lit a bit of leftover i had spilled and it did seem to behave differently to my previous mixes so the wax may have had an effect but i cant be sure untill tomorrow when i can jolly off down to the woods.

[Asteroid]

No, just melt the wax then mix it into the powder. The more wax you use, the more it slows down the reaction so the less you'll need a baffle. The 27:40:48 mixture is tried and tested so if you like paraffin, start with that then adapt it for your needs.

Edited by Asteroid, 14 March 2007 - 08:08 PM.

[blackplasma]

its been a while but i went off to the woods and tried the cooked with wax composition....
hmmm... not the desired efect but a very good efect none the less, i managed to make a hand held flare or emergency torch, so if anyone has a need for something that will burn with a bit of smoke and a 6 inch flame for about 4 and a half mins ie a signal flare then melt 40g of sugar with 10g of wax add the kno3 60g and pour off the excess wax. took a bit of effort to light as i think my fuse was not in the comp far enough and had to resort to a lighter, but hey! back to the drawing board

ive got an extended tube 60/40 cooked to try and one with a restricted opening {choke} to test next but i might prepare one of yours asteroid. am i right in thinking:

take 13.5gwax 20gsugar 24gkno3 {27/40/48} powder and mix the kno3 and sugar,
melt the wax pour it in to the powder mix quickly and then pack it in to a tube
?

[BrightStar]

A bit off-topic, but looking for notes on smoke baffle construction I was a bit surprised to come across this:

Grenades and Pyrotechnics - Canada National Defense

Interesting stuff, including internal diagrams of various smoke and signal devices...

I might avoid constructing a 'SIMULATOR, PROJECTILE, GROUND BURST C1A1' for the garden though!

Edited by BrightStar, 23 March 2007 - 02:23 PM.

[paul]

BrightStar, thanks for that detailed pdf! Very interesting reading. Especially Page 150,151 and 152 show how the baffles are used. They´re also used on page 52.

All these compositions used by the army are chlorate compositions. White smoke often is archived with HC-Smoke, which is a risk to your health in any way.

These compositions burn with a lower temperature than exisiting KNO3/Sugar/Wax compositions anyway. This yields the conclusion that it is harder to cool down the smoke stream preventing it from ignition.

I did alot of tests with KNO3/Sugar/Wax compositions and nearly everytime the smoke ignited. Only when it was very windy outside, the smoke screen was very thick and opaque.

I guess I should´ve used one or two of these "baffles". I think I´ll repeat these tests when I got time for it.


Edit:

I tried the old formula (I THOUGHT I did!) 5/5/2 KNO3/Sugar/Wax again.
Melted the wax, put in the finely milled smoke mix and mixed it very well.
Rubbed it through a screen and got a lovely freely flowing white powder.

Hammered 20g of it into a 30mm ID tube and ignited it (no plugs whatsoever).
The last time I tried it, not even to some extend so much smoke was produced.
I had to extinguish it with water So I thought about it...

Bingo! I had used a 10/10/2 formula instead. It gives off really really thick smoke. I think I´ll film a few grams of it. cYa later

Edited by paul, 25 March 2007 - 11:24 AM.

[blackplasma]

more tests done...

20/24/14 sugar/kno3/wax melted the wax, mixed with the mixed powders and put in a tube
visco fuse failed to ignite the comp so a few miniutes with a cigarette lighter and it finally ignited, burned great untill it got blocked with the leftover burned stuff so i squidged it to loosen the spoil and shook it out the end, burned well for a while but blocked again and went slow.

so i tried 20/24/12 as this appeared to saturate the powder but not too much, put it in to a petri dish type tube {3" diameter and 1/2" long} doubled up the visco and tried again, fuse failed again but when i finally got it going it ignited the crappy tube and produced no smoke untill i blew out the flames

so i went back to the trusty if not violent 60/40 kno3/sugar but this time with a baffle of a penny washer glued on to the end of the tube with a glue gun it started well and the baffle was doing a good job by reducing the flame to the size of one of those jet lighters, untill the glue melted and the washer flew away..

back to the drawing board and i discovered that the screw cap of a large wkd bottle fit snugly down my tubes so i made more comp and used the bottle lid as a baffle by punchine 4, 2mm holes in the top.
upon testing the baffle did a perfect job until it was melted, and the smoke was THICK. so i am going to try a new version soon with a stronger baffle and maybe 2 with an extended tube giving a cooling chamber at the top

also will try the new wax comp mentioned above how do you ignite it? visco?