1827 11 Sept. 3/4 The penknife blade was open.
1955 K. Hutton & A. Swallow viii. 100 Scoop a small conical hole in a charcoal block with an old penknife blade, and fill the hole with lead oxide (litharge).
2003 (Nexis) 27 Feb. 21 Any spongy or hollow-sounding timber that's easily pierced with a penknife blade should be checked by a professional.