Last month I bought one of those pens which you can rub off your writings with a kind of rubber at the end of the pen. I was so happy because I don't need to use correction pens anymore, so I did all of my maths exercises with that pen. One Friday, my books was very heavy so i left some inside the car. On monday when I take it to school, open it, I discovered in horror that all my writings has GONE. Some of them already became transparent, while some of them were still fading off. I was like wtf man, how can you be like this? Evaporated just because of a little sun??? In the end, I have to redo all my exercises. Can someone tell me what is the composition of that pen ink which makes it evaporate under heat? And my maths papers were not directly exposed to sunlight, it was at the bottom of one or two books and I kept them all in those plastic clear holders. Seriously what kind of witchcraft is this? Monster it is.