Quickie Test - Coloured Flames

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Date: 2005-03-12


I *finally* found a reasonable source of bulk Methanol in Australia. Technical grade Methanol for histopathology is quite cheap if you buy a large drum.

A small amount of Lithium Chloride, Sodium Chloride and Boric Acid were placed in seperate muffin-sized Aluminium pie plates and a squirt of Methanol added to each. The Methanol was ignited and the result filmed.

Additionally a small amount of high-purity Potassium Nitrate was tested in a similar manner.


Good effects.

The Lithium purplish red is a very beautiful colour.

Once the Methanol was consumed additional was added after cooling and again ignited. This could be done many times over, the colouring salt being consumed only very slowly.

Lithium Chloride is quite deliquescent and after being left out over night in ~50% RH it collected enough water to half fill the pie tray. This should not be a major problem in practice, as it would be dissolved into the Methanol before use.

If you use different coloured flames too close together the heat tends to cause small particles of the undissolved colouring agent to fly out of the dish and into the adjacent one, contaminating it and altering its colour. A proper torch should minimise any such effect in practice.

I tried some outside in the wind, but they did not tolerate it very well. A larger burner with a metal wick would probably have no major problems in moderate winds. This is something I will experiment with in the future.

In the past I've had problems with long-term use of conventional "alcohol lamp" style torches, the colouring salt gets concentrated in the wick and clogs it, also the salts tend to promote rapid corrosion of the metallic parts of the torch. The steel wool stuffed in a tin can approach discussed as on skylighter sounds promising and is cheap and disposible which is a big plus.


title type size
"Traffic Lights" Video video/x-msvideo 1.386 Mbytes
Methanol and KNO3 Video video/x-msvideo 666.212 kbytes
Methanol and Lithium Chloride alone Video video/x-msvideo 846.566 kbytes