[angeloposteraro]

I'm attempting to create a candle that burns with a color, I've tried soaking wicks in CuSO4 and mixing some in the wax neither worked, blue is  preferable but any methods or chem. suggestions are welcome.

[billnotgatez]

My initial guess is that you have a concentration issue. I could see no way that a wick soaked in copper sulfate could sustain a colored fire. Similarly, it seems to me that the concentration in the wax would also have to be fairly high.

Let me suggest an experiment.

Using a wire with a loop at the end (not copper) dip it in various concentrations of copper sulfate that has been mixed with wax. Keep the wax warm so it remains liquid and stir often. Start with a fairly high concentration of copper sulfate and dilute with wax between several trials.

That way you might determine the concentration needed.

A side note -
Most colored logs have the resultant gases go up a chimney and not permeate a room. I have no idea what effect burning a copper sulfate adulterated candle would have, since it lets the fumes go into a room.

[hmx9123]

Use a copper chloride instead (either I or II).  Chlorides deepen a flame color, and the copper chlorides in particular are known to give green-blues (plus don't have the pentahydrate energy soak like the copper(II) sulfate).

[angeloposteraro]

Thanks for the chloride idea, i did indeed try it to somewhat of a success, it sustained for a short while (30 seconds)  much more than the CuSO4. what i believe the issue to be it that the wick is coated by the wax, and the wick burns off the CuCl2 and the wax slows the wicks progress to the point where not enough new wick is being burned. i need something that wont decomp in the fire, nor will it burn off. either that or a non-polar wax soluble copper compound, or something else that will give a flame a distinct color.

[lemonoman]

From the copper sulfate MSDS:

"Burning copper sulfate may produce irritating or poisonous gases"

Just don't go inhaling the fumes on purpose and you should be OK....but you'd need a lot of Cu- compound (sulfate, chloride, whatever) to SUSTAIN the flame color...  Breathing in too much of it could cause problems.  lemonoman recommends ventilation ... especially since you obviously just want the color and not the scent.

[hmx9123]

Try suspending finely ground copper chloride in wax, then melt-casting your own candle.  Should have the same effect, but since it's burning the wax, it'll pick up the color better.  You've got a lot of sooty hydrocarbon from the wax, though, so you may have trouble with the nasty sodium line overpowering the green blue from copper.

[angeloposteraro]

From where would this sodium come ?

[angeloposteraro]

i tried melting some parrafin and i intended to add some CuCl_{2 (aq)}. but when i melted the paraffin and added the copper chloride, it stated bubling and turned black ? for reference the CuCl2 was obtained by a HCl + CuSO4, what is this black stuff ?

[angeloposteraro]

nvm, turns out the acid was reacting with the metal tin i was melting it in. so the HCl or H2SO4 was corroding the metal

[hmx9123]

Sodium contaminates everything, so you wind up with sodium lines where you wouldn't expect them.

I would add dried copper chloride to the wax, not an aqueous solution.  Suspending dry, powdered copper chloride to your wax MAY give you a green.  It's hard to say.  I've heard that boric acid can also give a decent flame color, but it's a much lighter color.  The copper chloride will burn blue/green pretty well.

*Edited - I meant to say boric acid, not borax, as the original post indicated *

[woelen]

You should get better results if you take your own unwaxed wick. Soak this with a concentrated solution of CuCl2 (not a mix of HCl and CuSO4, but true CuCl2) and let it dry.

Making a solution of CuCl2 is not hard. Precipitate some basic copper carbonate, 2Cu(OH)2.CuCO3, make this from copper sulfate and K2CO3, or go to a ceramics shop and buy copper carbonate. Dissolve the (basic) carbonate in just enough HCl (15% or so). No need to isolate the salt, just use the solution. Traces of impurities (e.g. sulfate ion or potassium ion) are of no concern, as long as the bulk is copper chloride.

The wick must be made really dry. Let it dry on a heat radiator at 60 C or so. When it is perfectly dry, immerse it in molten candle wax and make your own candle of this.