Back in 1979, the Papermate Erasermate was introduced to the world. It was a pen with "erasable" ink, and existed mainly to scare people who wrote a lot of checks. As far as I could tell, the trick was entirely in the attached eraser, a block of rubber so hard and rough that it could have abraded a knuckle-tattoo from the fingers of a prison-lifer. It was, in its first incarnation, junk.

Sharpie, the, erm, sharpie company, has just reinvented the genre. Instead of making an erasable pen, it has made a non-erasable pencil. How's that for smart thinking? The Sharpie Liquid Pencil contains an "ink" made from liquid graphite and lays it down just like a pen. Once written, you have three days to think on the validity and weight of your words. During this period you can erase it just like pencil-marks. After the three days is up, the pencil lines will turn to ink and remain inscribed forever.

According to the Sharpie Blog (yes, Sharpie has a blog) the new liquid pencil will be in stores from next month, September 2010. A quick look over at Office Depot shows that a version is already on sale, at $5 for two pens and six erasers.

If I ever actually wrote with pen (or pencil) and paper anymore, I'd be sold.

Introducing The NEW Sharpie LIQUID PENCIL [Sharpie Blog via Tim Carmody's Twitter]