Oiled charcoal is an interesting way to create a new drawing tool from willow charcoal. First, place the charcoal in a jar of linseed oil to steep overnight. The next day, remove it from the jar and wipe off the excess oil; you are now ready to draw with your oiled charcoal. This tool leaves a far richer black mark and cannot be wiped off the paper as easily as dry willow. You must use it fairly quickly though because, as the oil evaporates, it will become difficult to use.