DistractionGrating
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Blue candles?
If I wanted to make some paraffin candles that burned a nice blue color, could I just mix copper sulfate with the paraffin? If so, what would be a
reasonable concentration of copper sulfate to paraffin, w/w?
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Scalebar
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You'd probably want to concentrate on impregnating the wick with copper salts rather than the whole thing.
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TinSandwich
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That's a well timed question! Just last week me and some friends were desperately trying to make blue paraffin torches. Sadly all our attempts failed:
we took rags, wet them in a molten paraffin/cuso4 mix and wrapped them around a stick, we even tried sprinkling copper sulfate in between the many
layers of rags but the flame was still the regular yellow color after that.
It seems that the yellow/orange color of the paraffin flame "covers" the blue color of the copper sulfate flame.
You could try to get an alcohol burner (very similar to candles) and fuel it with a solution of methanol and cuso4 (sadly copper sulfate is insoluble
in ethanol), you could also try using CuCl2: it's a bit harder to find but it's soluble in ethanol and acetone.
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deltaH
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You can use polyethylene glycol as the 'wax' to produce blue flames, which you can colour with organic salts of the metal whose colour you wish to
impart.
See this patent for further details: http://www.google.com/patents/US3107511
The extra oxygen prevents the characteristic bright yellow colour of highly paraffinic flames, in the same way that alcohols burn with a blue-clear
flame.
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Marvin
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Copper on it's own produces a green flame. CuCl is the usual emitting species in pyrotechnic blue and if the flame/mixture is too hot it breaks it
apart and goes green. A solution of copper chloride in alcohol can produce a passable blue. Paraffin has particles of carbon producing the yellow
light thermally (black body radiation) and this swamps atomic emitters.
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metalresearcher
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When using CuSO4, you must use the white anhydrous version, not the blue CuSO4.5H2O crystals.
Just calcine the blue crystals by heating it to a few hundred degrees (but below red hot).
Water (vapor) + paraffin will induce the yellow flames.
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PHILOU Zrealone
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I have also thought about it...the wick is also part of the problem it contains charcoal and often sodium both providing yellow color.
Glass fiber wick also contains sodium but it express less (I have used glass fiber fabric rolled at the end of a woden stock to make alcohol based
troches (red, orange-pink, blue-green, green) for juggle. It is also less efficient to drive the liquid by capillarity than cotton wick does.
You need an alcohol gel containing traces of a halocarboxylate of copper (chloroacetate of Cu) and Cu(II) perchlorate.
You may also work with CuCl2(NH3)4 and Cu(NH3)4(OH)2 complexes...those goes more onto the electric blue side.
But beware of the toxicity for indoor...there is for sure a catalytic reaction happening leading to accrid, suffocating smel/fumes after a while.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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unionised
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Quote: Originally posted by metalresearcher  | When using CuSO4, you must use the white anhydrous version, not the blue CuSO4.5H2O crystals.
Just calcine the blue crystals by heating it to a few hundred degrees (but below red hot).
Water (vapor) + paraffin will induce the yellow flames. |
There are two reasons why that's known to be wrong.
The obscure reason is that people who run flare stacks add steam to suppress smoke and soot- that would make the flame bluer and less smoky.
The more obvious reason is that the quantity of stem released from the tiny amount of water from hydrated copper sulphate on the wick is insignificant
compared to that produced by the burning paraffin.
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Daffodile
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Somehow having Methanol burn, released from an inert and stable media would probably be your best bet. Not very bright though. Most Copper salts are
annoying as they emit no colour at low temperatures, and green at high temperatures. Good luck.
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DraconicAcid
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| Quote: Originally posted by Marvin | | Copper on it's own produces a green flame. CuCl is the usual emitting species in pyrotechnic blue and if the flame/mixture is too hot it breaks it
apart and goes green. A solution of copper chloride in alcohol can produce a passable blue. |
I thought it was green in the presence of halides, and blue otherwise.....
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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UC235
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Paraffin wax candles will not produce a blue flame. They burn yellow naturally because of black-body emission from soot particles produced in the
fuel-rich flame. Since you cannot blow oxygen into the flame to make it burn more completely, you need to use substances that have a lower oxygen
requirement for complete combustion. The small multicolor birthday candles sold commercially use trimethyl citrate as the fuel and burn clear blue
without addition of metal salt colorants.
I've tried (many many years ago) loading copper soaps into paraffin wax up until the whole mass was tacky and unusable. It gave a slight green tint to
the yellow flame and caked the burning wick with what was probably Cu2O.
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Daffodile
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| Quote: Originally posted by UC235 | The small multicolor birthday candles sold commercially use trimethyl citrate as the fuel and burn clear blue without addition of metal salt
colorants.
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So someone could potentially melt a bunch of those candles, mix with some solvent to make a glob, and coat onto torches? I'm just throwing ideas out
there so this probably wont work.
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