Colored Camp Fire Project, results so far and some questions

[billysundays]

Hello, new here. We're going camping this November, and one of the things I've been trying to figure out in preparation is an ideal way to add colorants to the flames. Sure, there are those packets with copper salts you can buy and just chuck 'em in the fire, but they're overpriced, I'm looking for a cheaper solution that'll last hours. This fire will be going for at least 6 hours, don't want to have to keep feeding the colorant every 20 minutes. Plus, I want the addition of red, which copper salts are not gonna produce of course.

 

I've been experimenting using a "wood gasifier" firepit. It burns way hotter than a normal campfire because by design it ignites any smoke that would otherwise escape, a more complete, stronger burn, and those pellets themselves put out significantly more BTU's than regular wood.

 

I've thrown in a spool of copper wire, which creates a decent enough green flame all by itself, but once you add a piece of PVC, a strong blue and purple flame is added to the mix. Very vivid colors. So far so so good- green, blue, purple, and orange. An interesting thing I noticed when doing this was that the colored flames wouldn't just emit out from above the copper wire, but would spread left to the other half of the pit where there was no copper, then up and out. Don't know if this behavior is because the fire is contained in a pit or because of the "gasifying" function of this pit distributing the gases throughout the pit, but this little experiment worked out better than I thought it would. It looked quite impressive. Cheap and simple enough. I wonder if the higher heat output helps or hurt the results?

 

What I'm trying to figure out now is how to add red. Really want red in the mix if I can manage it. Ordering some strontium carbonate soon, but I'm not getting my hopes up with that. Read several reports that the results are disappointing in a campfire, even with a chlorine donor. I'm gonna try a few things. First, I'll try making a firelog using paraffin and sawdust with strontium carbonate and chlorowax mixed in. If that works, I can make a log big enough to last several hours. If it doesn't work, I'll try strontium chloride instead. Don't have a plan C, so any suggestions are appreciated.

 

My other question; Its expected that adding PVC, a chlorine donor, into the fire with copper would results in the addition of a blue flame, but where the heck if PURPLE coming from? I can't find any explanation for it. If its the result of the combination of green, blue, and the orange/yellow of a normal wood flame, would that be from a subtraction color effect? Can someone explain exactly how that would work to create purple? And why doesn't this purple appear when using copper salts, which just results in blue?

 

So to sum up my questions-

• Has anyone had success using strontium to color a fire?
• Can anyone suggest a source for chlorowax?
• Why does copper metal, when combined with PVC/chlorine donor, in addition to making blue flames, also creates purple?
• Also, why is Skylighter going out of business??

Edited September 8, 2017 by billysundays

[NeighborJ]

This is just a hunch but I'd suspect the purple flame is the result of KOH being released from the charcoal. Potassium burns a lilac color without any chlorine donor. It is an atomic emitter and can wash out other colors. The choice of charcoal or firewood will limit the chance of KOH formation. Pine will be your best bet, oak is used to make lye. Again this is just a theory, but you can easily test other woods in your grille. What species of wood are you using?

 

Jason

Edited September 7, 2017 by NeighborJ

[OldMarine]

The easiest way to color your fire is to follow the instructions in this video. I tried it and it's my go to now. Copper pipe,old garden hose and fire!

[billysundays]

Thanks for the suggestion OldMarine. As far as using copper to color the flames, I think I'm good. Tossing in copper wire and a chunk of PVC or garden hose works perfectly, except no red color, and I needs me some red! Any thoughts on effectively using strontium would be appreciated.

 

Jason, thanks for the feedback. The bag of wood pellets I'm using doesn't specify a wood type, but I think the easiest way to test your theory later would be to throw in just some PVC without the copper and see if that creates any color alone, but I doubt its the case. Potassium makes lilac, but what I was seeing was deep purple, and I can't find any info online to suggest a chlorine donor would effect a potassium colorant, but I'm too curious now not to test this.

Edited September 8, 2017 by billysundays

[NeighborJ]

Well, the only other thing I can think of is the blue from a clean burning flame is mixing with the orange of a lazy flame to create a purple color. A torch can produce a nice light blue if enough oxygen is used.

[OldMarine]

For red just put some damp strontium nitrate in small thick walled tubes and toss them in as needed. If you want distinct colors that last you'll have to invent something new. Sorry.

[billysundays]

By damp, you mean moistened with water? That"s interesting. Why do you suggest strontium nitrate, as opposed to the strontium carbonate or strontium chloride? By tubes, do you mean PVC tubes? Not sure what you meant by the "distinct colors" comment, but thanks for the suggestion for strontium. I'll have to try and test this out.

[OldMarine]

Dampen it to get it to compact and allow to dry. Strontium Nitrate is hygroscopic and the added water makes it last longer in the fire. Just use a cheap thick walled pulpy tube. I like the garden hose/copper pipe method best.

 

I wonder if you could take sawdust bound with dextrin and loaded with the carbonates to make a slow burning colored puck?? I'll try this over the weekend!

Edited September 8, 2017 by OldMarine

[sora]

Many years ago I was passing by a small tobacco processing unit where somebody lit up a big pile of tobacco leaf and stem leftovers. The flame had a very nice pale blue shade to it much like a chicory flower. Later on I found that tobacco leaves contain Caesium and Caesium burns with a blue flame. Not sure though if caesium caused that blue color

[Arthur]

Try making a lump of cement/concrete/plaster mixed with your desired colourant the colourant should leach slowly into the flame.

 

Caesium burns with a blueish flame but it's so seriously expensive it's impractical. Plaster will offer the calcium orange colour. Get strontium nitrate, let it get damp and form it into balls like a tennis ball. in the flame of the fire it will release strontium over a time.

 

Don't cook food over a coloured flame.

[OldMarine]

"Don't cook food over a coloured flame."

 

Yum, barium burgers!

[billysundays]

Lol, OldMarine. You joke, but a strontium steak might not be the worst.

 

Last night I lit my firepit and made some observations.

 

I tried adding just copper 1st, then some PVC later, and then finally observed the flames die down with only the copper left. What I noticed was that the volume of the colors that comes off the copper has to compete with the color volume of the regular orange flame coming from wood. Just adding copper alone when the fire is going strong showed no color, but when the fire was died down, the flames were mostly green, even with no PVC at that point.. Adding chlorine (PVC) doesn't just add blue and purple to the flames, it also increases the color volume from the copper significantly, so that the colors can be seen among the orange flames. My guess from what I can tell is that the chlorine increases the color volume 10-fold.

 

For that reason, its important that whatever I make my log from doesn't also contribute any colors of its own that will compete with the strontium's red.

 

I'll order some strontium nitrate today to play around with and try your suggestions.

 

The other thing I realized was that the PVC was putting out an noxious smoke. The pit I'm using is called "Flame Genie". Its a "wood gasifier" pit design that creates a smokeless fire for the most part, so the fact that the PVC smoke was having no trouble escaping means I need to start working with a different chlorine donor soon that burns more cleanly. Any suggestions?

 

Arther, your suggestion to make a log from concrete/cement is interesting. What makes you think that might work?

Edited September 9, 2017 by billysundays

[NeighborJ]

Unless Arthur knows something I don't, the plaster has calcium carbonate as one of its main ingredients. This will prevent any color showing but a brilliant orange/red, even without a chlorine donor. Calcium is also an atomic emitter.

 

Calcium salts(orange), sodium salts(yellow), potassium salts(lilac) all don't need any donors to display their colors and will over power most other colors.

 

Arthur does have a good idea, a porous rock like lava rock can have a given salt worked into its pores without burning away, this is a good idea for prolonged colors.

 

Jason

[billysundays]

My same thoughts about the plaster.

 

Lava rock wouldn't work unless it had an open-cell structure, like natural sponge does.

[Mumbles]

Plaster is calcium sulfate, but the sentiment remains the same.

 

I don't think Potassium isn't going to be overpowering anything by the way. The color is extremely weak.

[Arthur]

The whole point of a plaster log is to give off calcium (orange) flame colour simply, cheaply, and for a long duration. Calcium salts are also essential for life.

 

Cement was purely an idea for a slow release binder for strontium salts, for a possible red flame.

[billysundays]

...Potassium burns a lilac color without any chlorine donor. It is an atomic emitter and can wash out other colors....

Jason, I was wondering if you could elaborate on this. What's an atomic emitter? And what flame colorants are enhanced by chlorine? I remember a Skylighter article that listed which flame colorants are enhanced by chlorine, but I can't seem to find it today. I'm just thinking about this because it seems to me that flame colorants that are enhanced by chlorine are much more effective as colorants than the ones that aren't.

[NeighborJ]

I can't seem to find a way to directly post the link but this pdf should help explain the difference between atomic light emitters and molecular visible light emitters.

 

www.jpyro.com>2012/08>Kos-710-731

 

It's mostly over my head but it details experiments done by Dr Shimizu and others in order to isolate the different color spectrum wave lengths for common pyrotechnic colorants. I'd try to explain more but I'd likely make a fool of myself and need to be corrected by someone more knowedgable than me.

[billysundays]

Thanks for the info Arthur.

 

Can anybody suggest a source for copper chloride (not oxychloride)? Thanks.

Edited September 13, 2017 by billysundays

[Maserface]

How much ya need?

[billysundays]

Just a pound to play with.

[billysundays]

I can't seem to find a way to directly post the link but this pdf should help explain the difference between atomic light emitters and molecular visible light emitters.

 

www.jpyro.com>2012/08>Kos-710-731

 

It's mostly over my head but it details experiments done by Dr Shimizu and others in order to isolate the different color spectrum wave lengths for common pyrotechnic colorants. I'd try to explain more but I'd likely make a fool of myself and need to be corrected by someone more knowedgable than me.

I meant to thank you for this info, NeighborJ, I got mixed up and thought it was someone else who added this. I agree, that paper flies over my head too.

Edited September 17, 2017 by billysundays

[DavidF]

What about lithium chloride? It makes a beautiful pinkish red when soaked into pieces of wood and thrown in a campfire. One thing that might be helpful is to somehow incorporate alcohol into the mix. A solution of lithium chloride in methyl hydrate burns a vivid pinkish red for a long time. A solution of boric acid in methyl hydrate burns a nice pastel green.

 

Obviously, you can't just throw the solution in the fire. But, if the solution could be wicked (asbestos?) from a container into the right area, it might do just what you want. Just thinking out loud here.

[Arthur]

There are a million things more user friendly than asbestos. Just don't go there for social purposes.

[billysundays]

Ha ha! Good point Arthur.

 

I would be ecstatic if lithium was an option, but its way too expensive. "Relatively cheap" is one of the parameters. If there were a way to make or find lithium salts at less than around $10, that would be my choice.

 

I don't even really want to use barium. All you read about it warns of its toxicity, but it seems likely it'll be the only colorant that could produce a strong green, comparable to cupric chloride blue. I have to look into the relevance of this toxicity. I mean, its not that I want to stunt my kids IQ, or turn my wife into a mutant, but I really really want green, you know, so I gotta weigh the pros of cons.