The charcoal in the
gunpowder mixture behaves like a black
body. As the charcoal is heated to sufficiently high temperatures,
it glows with a faint red color. As it is heated further, the colors
change from dark red to bright red to orange to yellow to white. By then
it is radiating photons with all the wavelengths that our eyes can see.
For materials like charcoal, incandescence occurs from about 480oC
to about 1400oC (896-2552°F).
metallic fuels, such as aluminium (3500oC/6332°F), magnesium (3200oC/5792°F)
and titanium (2900oC/5252°F), achieve high levels of brightness
when burned, so can be used to make the bright sparks that are given
out by many fireworks.
How are fireworks made?