| 摘要 |
<p>A disposable pencil has a lead formed in the pencil from a paste which solidifies on contact with the air. The paste is stored in the pencil body which has minimal porosity. The paste, formed of a colouring agent (90-99% by wt.) and a binder, is forced by a simple plunger device out through a porous tube at the end of the pencil. Holes at the upstream end of the tube admit air to the cpd., promoting hardening.</p> |
