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PostDate:2012-12-8 ViewCount:1836次
  As we all know, there is a soft hard pencil activities of points, pencils to write letter H, B and HB pencil said the soft and hard degree. Which is the origin.
  At first in the eighteenth century, Britain and Germany only produce pencil, launched in Germany to surrounding countries after the war, the two countries stopped to the French pencil supply, by force of helpless, napoleon let French a chemist in France land find a call graphite material, and then use this created the pencil. But the French they local graphite quality is very bad, and memory space is also not many.
  So the chemist in graphite added a kind of clay, and then release inside the kiln firing, this is the most advanced at that time, the quality of the best pencil refill. But with clay to graphite is according to the different scale, thus, burn pencil refill will have different hardness, and colour and lustre is gap.
  The H that letter's hard-core start, this means that the pencil hardness difference. So H this letter to the front of the number of, say the cartridge hardness is bigger, because in the clay in graphite with more. And the letter "B" means the soft and hard degree and font for write is clear.
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