[Kryptid (OP)]

Didn't know if this would count under chemistry or experiments; it's sort of both.

I have an idea that I am interested in trying; I want to make a candle that burns with a colored flame (hopefully multiple candles which produce multiple colors).

I plan on using metal salts (such as copper sulfate) to generate the flame colors. Since metal salts are ionic compounds, they will not dissolve in nonpolar substances such as paraffin wax. In theory, I could melt the wax and thoroughly mix in powdered salt. However, I feel that this would result in a flame of highly inconsistent color (since it would only "burn" grains of salt sporadically). One way to get around this, I feel, would be to use an alcohol-based gelatin. I am not sure it would work, but I would like to try to create a gelatin in which part or all of the water in the recipe is replaced by ethanol. I am also unsure if the gelatin would congeal properly with so much ethanol in it.

Since ethanol is a polar compound, the metal salts will likely dissolve in it far better than in paraffin wax. Dissolved salts should allow for a more even-colored flame than clumps of undissolved salt.

Does anyone have suggestions or critiques on how to improve on this concept?

[RD]

apparently it's been done before ... http://www.ebay.com/itm/PRISM-RAINBOW-MULTI-COLOR-FLAME-BIRTHDAY-CAKE-CANDLES-/230370193567

[Kryptid (OP)]

I find that funny, because not long after I posted this topic I found some colored-flame candles as well.

I might still try my technique and see if it works (hey, it's an excuse to experiment with fire and chemicals!).

[CliffordK]

It would be fun to try to make the candle. 
One of the issues you have to be aware of is "wicking". 

The way the candles or lamps work is that they suck liquid fuel up into the wick.  The goal is for the fuel to burn rather than the wick.

With this in mind, you would either have to have the wick suck mineral laden fuel from the wax,
or, perhaps you could use ordinary wax, and a mineral laden wick.

What would happen if you pushed some fine copper wire (from a small electric winding?) into the middle of your wick?

[RD]

What would happen if you pushed some fine copper wire (from a small electric winding?) into the middle of your wick?

I think only a small part of the flame would go green.

the colour-producing chemical has to be in the wax or lamp-oil for the entire flame to be coloured ...

 [ Invalid Attachment ]
oils are different for different colours

[Kryptid (OP)]

Nice suggestions everyone.

Now I'm just wanting to make flammable jello with metal salt in it (might be able to make a candle with it too). One of the problems I face is the fact that one normally needs boiling water to make gelatin. Replacing the water with boiling alcohol sounds like a recipe for disaster. If I could keep it under an inert atmosphere, it might be fine. I'm not sure how to do that, however. Is anyone aware of gelatin that can be created "cold"?

[CliffordK]

Pectin may also be used, but apparently it needs to be mixed with sugar and something to make it acidic.

I think you should be fine with bringing your alcohol up to, say 20°C below the BP.  I don't think I'd  use methanol, but ethanol has a BP of 78°C.  Butanol has a BP of 118°C, which might make it a preferable solvent, although perhaps not as good at dissolving ionic compounds, and more difficult to acquire.

I'm wondering if you could make a metallic soap?  Or just mix your soap with your candle wax. 
You should find lots of lye soap recipes on the internet.  Perhaps try adding other salts, hydroxides, and sulfates to the soap production.

[chiralSPO]

You can soak a wick in a solution of the desired metal salt, dry it and then dip it in wax--that should work but I don't know if it would be great.

Boric acid can give a really nice green color to alcohol flames.

As far as making gels, it will take some playing around with amounts and temperatures, but if you make a fairly concentrated solution of your desired metal with a counterion like acetate or benzoate and then add absolute ethanol or isopropanol very quickly the result can be a gel which will burn, and hopefully give a nice color to it.