In this tutorial demo how to make char-cloth indoors. Char cloth is carbonized fibers that will readily take a spark when trying to start a fire without matches or a lighter. Natural fibers such as cotton (linen, or jute) must be used. I also experiment with using dryer lint. The amorphous shape of lint such as cattail or dandelion fluff, causes a spark to smolder inward. It is best to throw sparks into this "char-bundle" after placing it in side an already prepared tinder bundle.
The process that the that has been converted is called pyrolysis. This makes the material into a slow-burning fuel of very low ignition temperature. It can be ignited by a single spark that can in turn be used to ignite a tinder bundle to start a fire. Depending on its source material and completeness of char, its auto-ignition temperature is between 349 °C (660 °F) and 455 °C (851 °F).
It is sometimes manufactured at home for use as the initial tinder when cooking or camping and historically usually provided the "tinder" component of a tinderbox. It is often made by putting cloth into an almost airtight tin with a small hole in it, and cooking it in campfire coals until the smoking slows and the cloth is properly charred. It is the equivalent of wood being made into charcoal and uses the same techniques. Char cloth ignites with even the smallest spark and hold a very hot ember, and is therefore commonly used with a flint and steel and fire piston.