Sal is my fav..... https://www.youtube.com/watch?v=FHw9DQHl9B0&feature=related"]salvador dali - YouTube
When you draw portraits do you think you HAVE to have different shades of pencils or that the same look can be achieved with just one and different pressures?
It is possible to get a full range of values using a single pencil. You have to use a soft one to do it though. I remember when I was in school that one of my drawing instructors gave us an exercise in which we were to use a 4B pencil to draw a portrait with values ranging from white to black. It was kind of tricky, but once I became accustomed to the softness of the graphite, I was able to accomplish it. You definitely nt to use a cover sheet when using graphite that soft, in order to prevent smudging.
