KGB Disappearing Ink pen
On the subject of spy pen, here is another. This time a pen that allows what is written to become invisible with passing time. Traditionally these types of pens have been available as children’s spy gadgets, but this one is for adults or it could be used by anybody for that matter.
During the infamous cold war between the US and the USSR the KGB had developed this disappearing ink pen. Now this pen is available for sale in the US and anybody can buy it off the net. The pen writes like a normal pen, but what is written slowly disappears, leaving a blank sheet of paper.
As the ink which was developed by Soviet scientists is a gel ink, you can write lightly and not leave indentations or marks on the paper. Apparently the ink is undetectable even under UV scanners and the writing cannot be recovered.
Once on paper, the ink appears normal for about 15 minutes. Then it begins to slowly fade away. After about an hour, it will have mostly disappeared, but will still be slightly visible. After about 24 to 48 hours it will have completely vanished! Even an inspection under ultraviolet light will come up with nothing. (Fade time and characteristics may vary depending on ambient environmental conditions.)
What can this be used for? You can use this to pass on messages which are going to be seen quickly. Apart from that probably all uses would be illegal – if you were sign dud cheques, legal documents, letters, pre-nuptial agreements, business agreements and the like, you could get into legal trouble and even be prosecuted for fraud. The KGB disappearing ink pen is available also from ThinkGeek.