A fun Saturday!

[Lloyd]

Every once in a while, I need a 'diversion' from the everyday design and making of stuff.

I was given a handful of green smoke stars by a fellow pyro who likes them, and wants to duplicate them. He asked me if I could analyze them.

Now... I LOVE lab chemistry, and even have a few appurtenances to the endeavor, but I am NO CHEMIST. So this sort of thing is always a challenge; fun, but hard.

First, I burnt a couple. They gave a black ash about twice the size of the original star, and a good gout of green smoke, with a burn time of about two seconds. They'd look good in the air. Next was trying to figure out the contents of them.

After 16 hours of fooling around (both last night and today), I've found that the formula is about 30% water-insoluble dye, of a mixture of yellow and blue dyes. I asked a chemist friend how to tell what was in there.

He had to remind me of paper chromatography, which I've done before.

I happened to already have some test strips which, along with the beaker I needed, I had to 'hunt down' in my stash. After finding the stuff, I did a quick run, and the colors separated nicely. I don't know WHAT dyes they are, but I know it's a mix of yellow and blue, and that it's not at all water-soluble, slightly ethanol and isopropanol soluble, and totally soluble in acetone.

Then I went to figure out what the flame package was. Almost the whole content of the star - except the dye - was completely soluble in an excess of water. That gave some clues. One thing that was left-over after cleaning out the dye from the residue is what appears to be about 2% elemental sulfur. At the same time I was doing that, I was trying another strategy.

I washed one star clean of dye in acetone. DAMN! There was enough dye in that one little 5/16" star to dye a white tee shirt a good green! It took nearly a quart, and about 25 changes of acetone to get that thing broken down to a fairly clean powder. Then, for some analysis of it.

Most "toy" smokes contain a phlegmatizer like sodium bicarbonate (required by APA 87-1), but this wasn't from a consumer item. I tested a small sample of the cleaned powder with acid -- no evolution of gas/CO2, so no bicarb in it.

I burnt a small sample. It gave a pure whitish/violet flame, indicating a potassium oxidizer. It left a clean white residue, evident of some sort of chloride or oxide from the oxidizer.

Could it be the oxidizer was KNO3? Well, KO is yellow, so probably not that. K2CO3 can result from burning carbon fuels with KNO3, and is white. Hmmm... but so is KCl. And I don't have any qualitative tests for KCL or K2CO3!

Ah... yes I do!

I know KCl is 'salty' in taste. This was. Oops! 'Turns out, so is K2CO3. THAT didn't work. Ah... but K2CO3 and acid evolves CO2 gas.

A drop of acid on a small bit of it revealed NO gas being evolved. So, it must be KCl. Even that doesn't tell me everything.

KCl could result from either perchlorate or chlorate as the oxidizer. And at this point, I only have documents to go by. Almost all colored smokes are oxidized by potassium chlorate (because it's cool-burning with carbon fuels). Because these contained no phlegmatizer, and didn't consume the dye during their burning, I have to assume it was the chlorate.

My conclusions are not quantitative -- I don't have the lab setup to do that. But I have books just loaded with colored smoke comps. So, in order to duplicate these stars, all I have to do is identify what dyes were used. I've done a LOT of internet searches, and cannot identify any yellow and blue dyes that are water-insoluble, barely soluble in alcohols, and completely soluble in acetone. (Maybe one of you might know!)

But, what a FUN diversion from my usual work! It was a good Saturday!

Lloyd

[richardh08]

Now that's what I call fun!

Like you, I very much doubt that the oxidiser is KNO3. Warming some of the original mix with a strong acid (ideally sulphuric, but hydrochloric will do) ought to distinguish between chlorate, which will decompose, releasing chlorine or its oxides, and perchlorate.

But I might be telling you something you already know.

[Lloyd]

Richard,
I did not know of that test. I have HCl (conc.), but not concentrated H2SO4.

I have more stars. So far, I've only consumed six of the (about) 25 given to me.

That's another set of notes to go in the chemistry documentation!

Thank you!

Lloyd

[Lloyd]

I have to say, also, Richard, that I had to sort-of "relearn" a bit of "strategic approach". Last night, I spent more time thinking about the process than I did any actual testing.

I had to develop an approach that wouldn't destroy the components I wished to test individually. The sequential order of the analysis was as important as the actual tests.

It was really enjoyable to refresh some old stuff I've not done enough of!

Lloyd

[richardh08]

When I wanted to analyse the sample of Chinese crackle, I had to relearn the techniques of qualitative chemical analysis that I hadn't used since my schooldays. Fortunately, I managed to find a secondhand copy of the textbook we used, and was able to put together all the apparatus to run an analysis on the semi-micro scale. I lack many of the specialised reagents that you need to do a full analysis, but it's surprising what a little ingenuity will do. The fact that I knew I was dealing with a fairly limited list of possible substances helped a lot.

But you are right, Lloyd, the order in which you run the tests is crucial, to make sure that each step doesn't interfere with later ones.

That smoke mixture is likely to have an organic fuel and I certainly don't have the means to anything other than the crudest of identifications of organic substances. For example, I was able to work out that the Chinese crackle was bound with some kind of cured resin with a phenolic base, but I still don't know exactly what it was, or how it was cured.

On that test for a chlorate, I would suggest you try it out on a known sample of potassium chlorate, to make sure it works for you and that you know what to look for. Please use a VERY small sample, and be careful; the reaction releases chlorine and its oxides, which are highly unstable.

[Lloyd]

"...be careful; the reaction releases chlorine and its oxides, which are highly unstable."
-----------------
Heh! Not to mention, "Toxic" and "tissue corrosive"!

Thanks... there's just as much of a chance that I wouldn't have known. Better safe than sorry. (and so-on).

LLoyd

[richardh08]

Yeah: those things, too!

I added the caution more for anyone else who might read the thread, so it was remiss of me not to mention ALL the hazards.

[Boophoenix]

Yeah: those things, too!

I added the caution more for anyone else who might read the thread, so it was remiss of me not to mention ALL the hazards.

Thank you Richard!

These things are so often forgotten and overlooked. I've battled with learning things threw the internet since my early days of starting to explore the cyber world where a lot of things are assumed when you are in a specific based area. Pyro isn't really any different as I entered it blindly and became kind of fascinated by all the things to learn and experiance. Unlike many other things I have tried to learn there are potential dangers in this adventure instead of just a simple failure to succeed. That failure might hurt physically or financially.

[sambo]

If you can find some battery acid and heat it, or the right drain cleaner ( check the bottle ) which is usually 96% H2S04 then you can add a drop of the concentrated acid to the white powder and if it contains chlorate will either heat and spit or spontaneously ignite ( assuming the presence of a suitable fuel ).

Of course, potassium nitrate will react with hydrochloric acid to form nitric acid and potassium chloride ( which will drop out of solution )

Finally, with respect to chromatography, I'm sure you know but if you had in fact a green dye originally that was a proprietary blend that would split out into its constituents, I don't know if that helps.

As you know, I am a chemistry lab geek so this one's close to my heart...

[Lloyd]

Yes, Sambo!

The heated acid test should discriminate between the perchlorate and the chlorate. But upon reviewing my results, I think I may already have reduced the selection to the chlorate. I used an 'excess of water' to dissolve the flame package... but I only used enough to dissolve it. And it was only a few ml. I'll have to go back and review (maybe even repeat) the experiment to see what the g/L dissolution was.

I suspect that - because of the relative solubilities of perc-vs-chlorate - that I'd have had some undissolved perc in the small amount of water I used.

On the dye thing. I already did a quick-n-dirty paper chromatography of the stuff, and it shows both yellow and blue. Tomorrow, when I receive my NARROW chromatography strips (don't want to waste the wide, multi-sample strips), I'll do a test with various solutions of solvent/non-solvent to get cleaner separations.

Then, on advice from a chemist friend, I've discovered that there are published charts of chromatographic separations of dyestuffs, so that I may compare mine to theirs to get a better resolution on what I have.

Also, another friend in the printing industry has told me that phthalocyanine blue BS and oil yellow are NOT water soluble, and only marginally-so in alcohol, but fully soluble in 'press wash' which consists of non-aqueous polar solvents. Acetone is polar, so that's a clue. I can mix water and acetone at different concentrations to get my different degrees of separation on the strips.

Thanks!
Lloyd

[Pyro]

I found this thread both entertaining and very interesting!

I have some smoke stars myself that I really would like to analyse. A slight problem is that they contain a core (not crackle, seems to be a black powder type of composition, I'm guessing it is there just to give a defined end to the smoke trail) so separating out a sufficient amount of the pure smoke composition will be a slightly bigger PITA than I was prepared for.

Any tips on how to proceed would be much appreciated!

[Lloyd]

Pyro,
That core probably IS a 'terminator'. We made a few types of smokes for the theme parks. They didn't look all that great when they just "petered out", but looked VERY good when they simply "snapped off". So, we made ours on dim BP cores, also.

Most of ours were used in mines, not shells. But I've done a few napthalene smokes in shells, and they seem to look OK, even when wound all the way up from the core.

Lloyd

[dave321]

Lloyd,

the yellow dye is most probably solvent yellow 33,the blue dye that's a bit more tricky
since there are several blue solvent dyes that work ( I think the one I use is solvent blue78), not the best but hey.
solvent blue 80 also rings a bell. Phalocyanine blue I found gives a washed out quite pale blue compared to the anthraquinone dyes. If you want a good white use Methyl anthraquinone ( red uses methyl Amino anthraquinone),
ok that's rambling off topic a bit …………..

I did a similar exercise to you on the low toxicity smoke pellet used in the L132A1 grenade (actually uses 2 pellets)and determined that it contained about 30% to 33% cinnamic acid. I couldn't finalise the composition however for other reasons, but its a good exercise to try