I've been watching an enjoyable course on Lynda.com about matting and framing. As the instructor, Konrad Eek, is marking his matte board for the initial cuts, he pauses for a moment to tell us that we should be using a 6H "architect's pencil," because it has a "hard lead...that leaves very little graphite residue." That's all the excuse I need to get a new pencil, although I would probably go for a Unigraph or Kimberly over that Turquoise.