Manufacturer: Pencils Etc
Brand: Pencils Etc.
Model: Test Scoring
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Many machine-read tests are still scored from cards marked with this pencil. Scantron and other manufacturers of modern optical test scoring machines recommend any HB #2 medium-soft lead pencil. There are no "standard" HB #2 pencils, however, because manufacturers worldwide have their own individual lead hardness criteria -- some even use an all-plastic "lead." Thus, this pencil thrives because it is made with a concentration of actual graphite whose opaque density ensures that it will trigger optical scanners.
Another real secret of its popularity is that it writes very smoothly, with a dark line. It is probably the most popular writing pencil among teachers, and crossword and sudoku puzzle enthusiasts.
Historical Note: There once were scanning systems that identified pencil marks by looking for their electrical conductivity. Electrical feelers at each end of the markable area made contact with that area and could detect pencil marks via the lead's ability to conduct electric current. To ensure enough conductivity, those forms had to be filled out with special pencils having high conductivity leads. The IBM Electrographic pencil was such a pencil. Pencil leads conforming to electrographic technology were often referred to as "mark sense" leads and were widely available until the late 1960s.
