This pencil and charcoal drawing, by JD Hillberry, is an excellent example of how it is possible to capture glass and other reflective objects, such as water using only pencil and charcoal. Here the artist has drawn a highly accurate still life image of a jar with three brushes in it.

I am considering using glass and plastic in my final image, as reflections open up a room. I'll therefore do my own pencil studies into the interaction between reflective objects.