Fuels and Burning Rates
Applications involving colored flame compositions will require either a long-burning composition or a mixture that burns rapidly to give a burst of color.
Highway flares ("fusees") and the "lances" used to create ireworks set pieces require long burning times ranging from 1- 30 minutes. "Fast" fuels such as metal powders and charcoal are usually not included in these slow mixtures. Partially-oxidized organic fuels such as dextrine can be used. Coarse oxidizer and fuel particles can also retard the burning rate. Highway flares often contain sawdust as a coarse, slow-burning retardant to help achieve lengthy burning times.
To achieve rapid burning - such as in the brightly-colored "stars" used in aerial fireworks and Very pistol cartridges - compositions will contain charcoal or a metallic fuel (usually magnesium). Fine particle sizes will be used, and all ingredients will be well-mixed to achieve a very homogeneous - and fast burning - mixture.