Carbon has the highest resistivity of all the elementsΓÇöitΓÇÖs resistivity is over 100 times greater than that of a metal such as platinum. To create the carbon filaments, Edison partially burned different materials until the material changed into carbon. Because carbon filaments could be very fragile, Edison used a looped filament, rather than a coiled filament. The filaments were shaped in molds before they were carbonized.
Bast wood (which is also called bast fiber) comes from the inner layer of the bark of certain trees. This type of fiber was just one of a number of different wood-based materials that Edison tested.
