| The first and most succesful
material used to manufacture pens. Natural rubbler is vulcanized whith approx. 30% of
sulfur by aplying heat and pressure. The hard rubber rods can be worked on the lathe, are
resistant to any agressive liquids and can be polished to a shiny gloss. The only
disadvantage is the tendency to change colour with light and water, as the sulfur then
turns up at the surface. Till the end of the thirties, hard rubber was the dominant
material for pens. Hard rubber can best be identified by the smell of sulfur (foul eggs). |
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