Colored flames

[MikeVDS]

I'm looking to generate colored flames. Mostly looking for green but all colors would be great. It's easy to find solids to add to flames to create different colors but I'd rather have another gas I could burn or mix with propane to get the desired color. It makes it easier to automate and control if I can just switch or mix gasses rather than trying to mix in a solid or powder. If anyone knows some gasses that burn with color or know a good system for adding powder to a propane flame let me know.

[Dustdevil]

Changing the color of a hydrocarbon flame, whether it be propane or another fuel is not all that simple. The nature of orange/yellow flame is difficult to overcome. For green I would suggest using boric acid or coppler sulfate. Mixed with methanol they will produce a very nice green for a low cost. If you wish to overcome the hydrocarbon flame you will need to inject copper chloride into the flame. Copper Chloride is a little more difficult to work with. It is very hygroscopic. Also, it will take large amounts to maintain the green flame. It will be much easier to inject a liquid into your flame that burns. Keep in mind that methanol requires nearly complete atomization to burn. You will need fairly high pressures and a means to atomize the fuel. The up side is you get a nice green color with little or no toxic residue. You can also achieve red, blue and lavender with other chemicals. Those colors will be far more expensive. PM me off list if you wish any more technical info.

http://www.flickr.com/photo_zoom.gne?id ... 413&size=o

[MikeVDS]

Well the main use I have in mind for the colored flames is a large dish lines with copper tubing that we run propane through to make it a large flaming dish. I'd like to be able to change the color of the flames. The gas doesn't need to be a hydrocarbon. As you can imagine it would be fairly simple to run another gas through the lines. Adding a solid will be quite complex. A liquid like the methanol/boric acid mixture that you suggest would be easier than a solid but would require a pump or pressurized bladder or similar device to get it to flow. Also normal holes in the copper tubing covered with steel wool work well for propane but probably would have to be altered for a liquid. I may look into those mixtures you suggest but it would be much easier if I could find a gas that likes to burn another color than the orange/yellow. Bringing another pressurized tank of gas and a T is much easier than making the system work with atomized solids or liquids.

[Dustdevil]

Of the gasses that are practical to use, you will not find one that burns with a colored flame. With the correct air/fuel ratio most gasses will burn blue or white. If you have a ratio that is too rich with fuel, hydrocarbon fuels will burn yellow. Propane, natural gas, mapp gas and acetylene will all respond about the same. Hydrogen will have no color unless contaminents are introduced. That is why many glass blowers fuel their torches with hydrogen, it is so pure. The colors are created by adding various salts to the fuel. I suggested methanol because it mixes well to create colors, it is inexpensive to purchase and it is safe to work with. Ethanol does not do well with color changes and it is quite costly. If you are looking for something simple, you might try using STAINLESS steel wool and pre soaking it in various highly concentratedsolutions. It only requires about 3ppm of lithium chloride to change the color of a flame to red. Steel wool will break down too quickly and "contaminate" your colors. You could run a separate copper line for the color effect and bring in that pressure when you desire colorants. I have not tried that, but I believe it would give a color change. I do not know how long it would last, however.

[MikeVDS]

I had not really considered bringing in more lines for the second fuel but that might be an option if nothing easier exists. Seems the easiest way to do this would be to pressurize the methanol mix through nozzles with some sort of igniter? Mister type nozzles are easy to come by and work well at around 50 psi. A pump would not be too hard to set up considering that we may have a generator near by running anyway to power a heat blanket for our propane cannon. Sounds like a possible way of getting some green flames.

[TronaFaerie]

I just had a thought, could you put a wire of the desired metal in the flame. Anyone know if propane burns hot enough to do this? I'm used to bunsen burners. You still wouldn't burn purley color, but you could get color towards the center, if I'm remember my flame testing correctly.

Darn all this, I'm probably still a newb by most standards, but this is a great way to let out my geekiness.

Lotsa Love,

Trona

[MikeVDS]

It's not a bad idea but how would you get it to automatically feed? Ease of construction is a factor for this project. :)

[robotland]

Maybe you could lay hands on a partially junked wire welder, and use the feed mechanism for the wire. A clockwork feeder would sure look cool, though....

[Rocket75377]

This was touched on in a previous post, but one of my favorite parlour tricks is methanol (Sterno) and Boric Acid (can be found at your local dollar store sold as roach poison). It makes a really neat green flame, and the boric acid tends to cause the gel to liquify. You end up with a melted-Jell-o consistancy paste that's really neat to spread over whatever.

[robotland]

On a recent field trip to Gander Mountain I found sticks designed to create different color effects in a campfire- Unfortunately they did NOT list the chemical ingedients. About the size of a small road flare, and a coupla bucks each. If I need a science project to combat Winter Boredom, I'll get one and give it a try.

[EspressoDude]

One way to get wire into small particles is with a metallizing gun. This is a fixed or hand held unit that takes wire and either "grinds" or melts it and sprays it out a nozzle. When I was in the navy years ago we had some that were used to build up worn shafts and stuff. Great fun to watch as the air power grinder powered up(sound like a air die grinder), and then the stream of molten metal, sparks and all.

here is a link to some info on this idea:
http://www.gordonengland.co.uk/cws.htm

[Dustdevil]

The sticks you refer to are generally made from Copper Chloride, Copper Sulfate and Strontium Chloride. These burn will with little or no toxic discharge. If you wish to inject particles into a flame that can be done very inexpensively with a small hand held sand blaster. These are used by body shops for clearing the rust from tight corners. They can be purchased on Ebay for under $20. I use Titanium particles and various chems in mine. If you look at the fifth picture is this series, we just switch to boric acid and a crew member was injecting Ti particles into the jetstream. After we spooled the engine up to 75% thrust, the sparkle effect went up about 120'. We power the sand blaster with Nitrogen that we tap off of our liquid fuel pressure tanks. It takes one bottle per show if we use the sand blaster.
http://www.jesshobbs.com/brc2006/eldiablo/index.html

[MikeVDS]

That is awesome. Thanks for the tips. We've been working on our flaming cauldron for the last few weekends and had given up on possibilities of doing it on the cheap or easily (which meant not for 07 with our other projects going).