Okay, so maybe I'm overreaching a bit, looking for grand patterns where there are only tenuously associated facts, but I think this minor anniversary actually reveals the soul of America:
- Sunday marks the 145th anniversary of a great marriage. On that date in 1858, the first patent was issued to Hyman Lipman, an inventor from Philadelphia, for attaching an eraser to a pencil. Unfortunately for Lipman, the patent later was ruled invalid because officials said his invention was just a combination of two existing things, not a new use.
Hey, it was still a good idea, and we'll celebrate erasers anyway.
What you want the eraser to get rid of - black pencil, color pencil or ink marks - determines its makeup. Erasers made for graphite in black pencils work by adhesion, lifting the mark from the paper. But ink soaks in, so in that case an eraser is needed that actually removes the top layer of paper. Some erasers also contain small amounts of solvents that dissolve ink.
....Pencil erasers are made by putting blended ingredients into a heated machine called an extruder. The compound is pressed through a nozzle, producing a long ribbon eraser, which then is cut into smaller lengths. Synthetic rubber erasers are vulcanized (cooked under pressure) to cure the rubber, but vinyl erasers skip this part.
After being cooled in bath water, erasers are chopped into plugs, and the synthetic ones are tumbled to create their round edges. A rotating hopper lines up the plugs and sends them down a conveyor belt where they're ready to meet the ferrules (the bands of metal on pencil ends). Plungers push glue-filled ferrules onto pencil ends, and others fill them with plugs.
And why don't pencil erasers last as long as the rest of the pencil? Manufacturers are mum, but one company rep was heard mumbling, "Maybe if people didn't make so many mistakes . . ." [Cleveland.com]
The article also tells us that "most pencils sold in Europe are made without erasers." So, an American attached an eraser to a pencil 145 years ago and the Europeans still don't put them together. What does this mean?