Sciencemadness Discussion Board - Relatively safe impact smoke grenade ideas?

Relatively safe impact smoke grenade ideas?

Hockeydemon - 7-5-2013 at 00:41

Seeing as the other thread on impact deflagration devices was closed for getting off topic, and being unsafe. I would like to get that conversation back on topic because I think we could come up with a relatively safe way to make a 'smoke grenade'.

After searching around I found someone who made a pretty decent 'torinoko' on youtube by utilizing the caps from a cap-gun wedged between two rocks surrounded by flash powder from firecrackers, and wrapped in toilet paper.

Now Armstrong's mixture kind of scares me, but I really don't want to sit and take out hundreds of little caps either. I feel that there must be a reasonable way to make small quantities of Armstrong's mixture at separate times from matches, and some oxidizer (suggestions?). In my mind I would like 1x1" paper squares - though I truthfully cannot speak to the dangers of this so your wisdom or suggestions would be appreciated.

Next comes the task of smoke production. After looking at what the military uses I quickly decided I am not overly interested in hexachloroethane/zinc, terephthalic acid, or WP mixtures. These are all unreasonably toxic for a fun toy IMO. After searching around I found a neat (free) publication from a laboratory who went about trying to find a replacement smoke grenade coming from a safety aspect (I believe for military training purposes). Here is the link to the .pdf containing the publication - I'm sure some of you will find something interesting in it.

Here is the abstract:

Quote:

The compositions made were containing various amounts of NaClO3, cellulose, CaCO3 and Mg (from two different sources). From the laboratory scaled tests the composition named “11EM0745” was the best performing composition made. When these compositions are compared to the benchmark obscurant compositions (HC smoke, red phosphorus smoke, and TPA smoke) it is concluded that the transmissions through the smoke of the new sea-salt compositions are much higher compared to the HC and RP smoke, but lower compared to the TPA smoke. The smoke from developed compositions are less toxic than the HC, RP and TPA smokes.

I think their composition (ratio's provided) is reasonably safe for a fun toy. However I can't say I know whether or not it is feasible to use an impact ignition source such as Armstrong's mixture in order to light it. I'm open to suggestions here also.

Last but not least comes the containment vessel. I guess this would depend on what is required for an ignition source, but continuing with Armstrong's mixture until I'm given a better idea.. I was thinking eggs? I'm not exactly sure how to make a straight cut around an egg, but it has to be possible. Eggs are incredibly cheap - you could cut them in half, remove the contents, place a piece of that 1x1" Amstrong's paper in the egg with some sort of abrasive material upon it. Then fill the egg with the smoke mixture mentioned before hand - then simply use super-glue to close the egg back up (or tape idk).

Hopefully this sparked some sort of ideas on how to go about this. It needs to be relatively safe to use, and I would like that it not leave behind something potentially hazardous such as glass shards, chemicals ect..

Bot0nist - 7-5-2013 at 05:29

Remember, these pose a serious fire hazard. starage is a no no, and whenever, whoever is handling them they must be ready for it to light at anytime.

A small amount of Armstrongs mix can be had from matchbooks and KClO3 from the bleach. just wash the impure phosphorus with plenty of atone to remove most of the adhesive. And for gods sake, ever mix more than a couple 100mg. It is sooo easy to destroy your fingers and eyes with even little bits of armstrong mix. I doubt it is the best choice for your project anyways.

Maybe a couple R candy ball with a small patch or spot of KClO3/sugar and think up some way for a tiny amount of H2SO4 to come into contact with it, when ignition is needed.

IDK though, its not an easy problem without some good engineering.

Hockeydemon - 7-5-2013 at 05:44

What is it that makes the little papers from cap guns 'less reactive'? I get that they are obviously small, and contain a minimal amount of Amstrong's mixture, but I remember playing with the little papers from the caps when I was younger. How would I go about calculating the catalytic amount of the mixture I'd need in order to ignite the mixture composition described in the publication?

chemcam - 7-5-2013 at 08:33

I don't think your ignition source is going to work very well, two scenarios for you, you fill the egg with powder because that has the best properties for ignition. You throw the egg, hits the ground, powder cushions the blow and nothing happens other than your mixture is now around outside the broken egg shell. Scenario 2, you throw the egg it hits the grounds, this time the charge goes off but the explosion spreads the smoke powder out so thin it burns within 2 seconds, more like smoke blanket.

I think this topic is more about engineering, and not possible by a home chemist, at least a safe one is not possible. If you use a metal container you cant have the charge in the middle or it will explode without a proper vent hole anyway.

If I were forced to make an impact smoke grenade in an egg shell I would forget about explosives and just do the process in an inert atmosphere, and I would add a certain amount of pyrophoric metal into the smoke mix and make sure the seal is air tight.

That is a lot easier than it sounds trust me, I use argon atmospheres all the time for welding aluminum and for certain experiments.

This is a throw down bang-snap I made with SA*DS you could do something like this but use much less if you are stuck on igniting with explosive material.
SA*DS Bang Snap 1 (from distance)
SA*DS Bang Snap 2 (close-up)

[Edited on 5-7-2013 by chemcam]

Finnnicus - 7-5-2013 at 15:23

Hey chemcam, on an semi-related note. How hard is it to get argon? Price? License?

Bot0nist - 7-5-2013 at 16:28

In the usa. Easy peezy. 18 or older and i think it is OTC...

chemcam - 7-5-2013 at 16:31

Quote: Originally posted by Finnnicus

Hey chemcam, on an semi-related note. How hard is it to get argon? Price? License?

Very easy to get it, no license needed, I forget the cost its been a while since I needed a refill, my tank is huge. For MIG welding you need inert atmosphere so the weld doesn't oxidize. Some though are mixed gas cylinders which are argon and CO2. I have both kind along side oxygen and acetylene, I had a nitrogen tank but I left it out front and it got stolen.

Finnnicus - 7-5-2013 at 17:32

Back to the subject, I yet again recommend strike anywhere matchheads for the amateur. They work great, but I can't buy more here in Australia.

Hockeydemon - 7-5-2013 at 23:42

<HTML>
<Body>
Here is the composition I feel has the best chance of working, and the data they acquired while testing it. Any thoughts?

Why is this space here?!
<table border="1">
<td><td>Composition(wt%)</td>
<tr>
<td>NaClO3<td> 69%</td>
<tr>
<td>Cellulose<td> 23%</td>
<tr>
<td>Mg<td>3%</td>
<tr>
<td>Oxbal (%)<td> 2%</td>
<tr>
<td>Solids (%)<td>45%</td>
</tr>
<tr>
<td>Friction Sensitivity[N]<td>Relative Humidity %<td>[Temp C]</td>
<tr>
<td>120<td> 47.1%<td> 17.7C</td>
<tr>
<td>Impact Sensitivity[Nm]<td>Relative Humidity %<td>[Temp C]</td>
<tr>
<td>30<td>47<td>18.1</td>
</table>
</body>
</html>

[Edited on 8-5-2013 by Hockeydemon]

APO - 10-5-2013 at 00:05

I started a "Deflagration On Impact" thread, but it got away from me and it was closed since people started talking about 3kgs of APAN (which is crazy), but in the mean time I thought maybe some magnesium/ferrocerium could be a start.

Dornier 335A - 10-5-2013 at 12:07

I have some experience with impact igniters.
My solution was to make a device that was ignited by strong acceleration in one direction only, rather than have something that ignites on contact anywhere. This makes it much safer to handle and store.
Here is a small diagram:

The whole thing can be as small as a few cm long and 5 mm thick. The primary of choice is Armstrong's mixture with coarse magnesium powder. It deflagrates relatively slowly with a hot flame.

To further increase safety, this can be stored separately and inserted into the smoke mix just before use.