(left) "Arc"
Charcoal and chalk on
rust colored Canson paper, 11"x7.5"
©2013 Diana Moses Botkin
Although I usually sketch with willow or vine charcoal and occasionally use charcoal pencils for detail, I'm trying out some sticks of compressed charcoal.
I have used it in the past but it has been awhile. One can get nice darks with the stuff, but it is different than using the natural charcoal.
Natural charcoal (such as willow charcoal) is carbonized wood, having been burned over heat with incomplete combustion. Compressed charcoal sticks are charcoal powder mixed with binder. The amount of binder determines the hardness of the stick.
For my use, willow charcoal is an easy medium for sketching the model, especially in quick poses. I can make fast changes with only a swipe of my hand or the end of my shirt (one more advantage to wearing black.)

These drawings were both drawn with compressed charcoal sticks and charcoal pencils. White highlights were added with the white sticks and pencils.
(left) "Looking Up"
Charcoal and chalk on
grey colored Canson paper, 11"x7.5"
©2013 Diana Moses Botkin