- Take a hexamine fuel tablet and put some chromium(III) oxide powder on top of that.
- Set the fuel tablet on fire to heat up the Cr2O3 powder.
- Then cover the fuel tablet with a glass to stop the fire but not long enough to allow the Cr2O3 poweder to cool down.
- Remove the glass.
- Now the Cr2O3 poweder will heat even stronger. It will stay red-hot until the hexamine fuel tablet is spent.