Green Fire Jack-o-Lantern Materials
- carved jack-o-lantern. Traditionally this would be a pumpkin, but you could use a watermelon, cantaloupe, etc.
- boric acid (usually found in pharmacy section of store)
- methanol (I use Heet™ fuel treatment, found in the automotive section)
- aluminum foil or heat-safe container that fits inside your jack-o-lantern
- long-handled lighter
Technically all you need to do is sprinkle boric acid in a heat-safe container, add a little methanol, set the container inside the jack-o-lantern and light the fire. It's important to use a long-handled lighter, since the vapor pressure of methanol is very high and you will hear that 'whoof' sound when you light the mixture.
The best result, in my opinion, comes from lining the inside of the jack-o-lantern with aluminum foil and using the pumpkin as the heat-safe container. You can sprinkle boric acid inside the jack-o-lantern, splash a little methanol around, and light the decoration. Do not add more fuel to the burning fire; wait until it goes out. Safety note: don't do this indoors!
Holiday Clean-Up Tips
The green fire can get very hot, so there is a good chance your pumpkin will get somewhat cooked by lighting it this way. The methanol is burned away by the fire, leaving some boric acid residue with your pumpkin. While boric acid is not particularly toxic, you don't want kids or animals to eat this jack-o-lantern, nor would I advise using it for compost since too much boron can be toxic to plants. Be sure to throw your jack-o-lantern away before it rots in place. This is highly hypocritical of me, since I haven't actually cleaned up a jack-o-lantern since... well, never. They do get scarier when they rot, after all. Just remember the pumpkin contains boric acid, so don't let anyone eat it.