Charcoal is made by heating twigs without oxigen, thereby removing liquid parts and turning the wood into carbon. Drawing with charcoal has the following (dis)advantages (depending on how you look at it):
-it is very hard to make sharp detailed work
-you can use your hand or a “blending tortillon” to make soft cloudlike transitions
-if you want to store your charcoal drawing you have to fix it with fixative; the carbon parts don’t stick to the paper by themselves
-in contrast with the silvery graphite of a pencil, charcoal is really matte black
-you can break off a part of the charcoal stick and use the length to quickly cover a large surface
In lesson 2 of the beginners course we drew a bottle and a wineglass against a dark background.
The subject, with the shiny highlights, transparent parts, and the folds of the cloth in the background, forced the students to think in dark and light. In lesson 1 we worked with pencil, making it difficult to create soft transisitions by shading or hatching. With charcoal this is not the problem, you automatically start seeing the big shapes, and this is great preparation for painting. A useful technique in working with charcoal is creating the highlights by using a kneaded eraser. To make dark parts even darker you can fix them first and then add a second layer.