Thanks Carl,
For this I used Conte pencils, the colors 'espresso' and 'white' (Prismacolor Color Premier) . I have about three of each color and was constantly sharpening them. I pretty much went through two of the espresso colored pencils and one white. I have used nearly every type of sharpening process imaginable over the years and that which satisfies me the most are simply the old hand cranked sharpeners we had in school. I have a Bostitch attached to the wall in my utility room. I hate the electric sharpeners, with a passion. Using a exacto knife for a long point has it's advantages, but can be time consuming and will it require one to hone that particular skill. All pencil work requires patience and a lot of pencils to achieve a high degree of execution. I probably have 300 or more pencils in my studio.
You can read the thoughts of the superb graphite artist Allen Williams on his website's FAQ page concerning the materials he uses.
http://www.allenwilliamsstudio.com/faq