An artist can use charcoal lightly for a soft, erasable mark or press harder for a dense dark area. Loose or vine charcoal often lifts more easily; compressed charcoal contains a binder and tends to make stronger marks that are harder to remove. Paper texture also changes how much pigment catches on the surface.
These properties make the material useful for quick studies of light, shadow and gesture. Choosing a kind of charcoal is part of choosing how much a drawing can be revised.