[remuze]

Hello everyone,

My mum bought my dad these 'fire color cones' for christmas last year and I have been trying to reproduce them at home to give to people for christmas. They say 'contains copper sulphate' on the box and after searching around on the net I found many places explaining how to make these. They suggested 1lb of chemical per gallon of water so I bought 500g of copper sulphate pentahydrate and mixed it with 4 litres of water, giving a blue solution (so far so good). I then took around 30 pine cones and soaked them in this solution for around 24hrs, until they had all closed and looked very sorry for themselves

After drying them for around 5 days, until they had all opened again and formed a lovely crystal coating, I tested the first one. I did not see one blue flame. Nothing at all like the ones i purchased that created blue and green flames for over 10 minutes! Thinking I just had to go stronger I bought another 2kg of copper sulphate and made the solution saturated. At 20 degrees celcius this was about 300g/L or something similar. I repeated the process and still I did not see one green flame.

By this point I was scratching my head trying to work out what was going on, so I took a handful (not with my hands) of the powder and threw it directly on to the flames, no effect?

Any suggestions on why this might be? Is it because it is pentahydrate? I assumed the water would be driven off fairly quickly, there is still a good amount of copper in the solution somewhere surely?

I'm stumped so any suggestions are greatly welcomed,

Cheers!

[Sophia7X]

I have gotten this to work by making a solution of (~90%) methanol and boric acid (commonly found in roach killer). All you do is drench the pine cone (or anything, pretty much) and then light it. Nice emerald green glow. You can try dissolving the copper sulfate in alcohol. When you light it, it takes a few seconds for the electrons to get excited and fall back down, giving you that nice green color.


I have also gotten this to work by coating something with ethyl alcohol based hand sanitizer (63%), adding a layer of powdered boric acid, and putting more hand sanitizer on top.

Since you want to give away the pine comes as gifts, however, I recommend you dissolve your crystal in ALCOHOL (Heet is good solvent) not water.

By the way, test your copper sulfate by putting a bit of powdered copper sulfate on a wooden splint or something and test it for color by holding it over a small flame  rather than throwing it directly into flames. That way, your color won't be swallowed up. Sometimes sodium contamination (sodium burns yellow) will dominate over the actual color too. If that's the case with your sulfate, try getting some boric acid.

Being a pentahydrate isn't the reason. Its the Copper(ii) ions that matter and give off a green color. Also, you really do not need that much copper sulfate since it isn't a fuel that's getting used up.

[Arkcon]

Additionally, you may want to try a variety of pine cones.  The resin on the tips makes for a nice smell, and helps them burn, but may prevent a water solution of salts from soaking in effectively.  Again, what Sophia7X: suggests may work better, the alcohol can cut through the resin better.   The vendors know exactly what species of pine cone to use, try to match them, or just try different species.  If you use water, you want the pine cones dry enough to burn, but too dry can ironically, prevent the color from appearing -- the cone just flashes into flame, you see some color around the edges of the flame, and its gone.

[hmx9123]

You need to use copper chloride.  Colored flames are generated in many cases by chlorine donation inside the flame envelope, and copper is no exception.  Start with a saturated solution of copper(II) chloride (not particularly great solubility) and let the pine cone soak in it for a month.  Then pull it out, let it dry fully (weeks) and burn it.  Do several pine cones at once to save yourself some time.