A magnesium ribbon is held with tongs and lit with a match or torch, making a bright flame that consumes the ribbon from the bottom up.
The ribbon should be about 20-30 cm long. Hold the ribbon with the tongs high and at arms length. Let the magnesium ribbon hang at a steep angle but not vertical. Light the bottom of the ribbon by bringing the end of the torch flame up to ribbon. Magnesium will melt before it lights, so carefully with the torch. The ribbon can also be lit with a wooden match.
Wear safety glasses and don't look directly at the flame.