I've been using these pens for a while now, and appreciate their «Undoí¢â‚¬Â feature: namely being able to erase with the rubber end what I've just wrote.
Description from Pilot's website:
These new pens from Pilot erase by FRICTION, they are like a magic pen for adults! The pens have a special rubber end to rub the thermo sensitive ink away with, thus no eraser by-products are produced, yet the ink disappears magnificently (and the rubber never wears out!) The pen writes smoothly, in silky black lines, and erases without a trace!
Brilliant and very popular with my children, or at least until last Tuesday..
Mathias came home with a physics exam that got crumpled in his bag and was looking for a way to smooth the paper out. That's we suggested to give it a quite iron. Just a little heat to uncrease the paper, but that was without factoring in the ink's thermo sensitive propertyí¢â‚¬Â¦
We wiped the sheet clean of all of Mathias' writing. There was nothing left. No name, no date, no results, no diagram, no nothing except for the teacher's corrections and markup in red ink. Nothing, nada, ziltch.
Gasp. Glups. Rats.
There was nothing much else for us to do than to write a note of excuse explaining the ordeal and to count on the teacher's sense of humour. We'll know more about that episode when Mathias comes home from school tonight.
Nevertheless, there is hope as I fell on the following paragraph this afternoon on JetPen's website:
Interestingly enough, the ink in these pens will actually reappear when the temperature reaches below í¢â‚¬â€œ 10 C (under 14 Fahrenheit). A freezer is sufficiently cold enough to make the ink start to reappear. It is like a magic pen for adults!
Never give up.