Rubin Samuel. The Secret Science of Covert Inks

Washington: Loompanics Unlimited, 1986. — 138 p. — ISBN: 0-915179-44-X.This is a reference volume for those desiring ready access to information about the covert inks used by criminals, intelligence agencies and others. Except for the limited instruction in spy centers, there is no course in covert inks available to enforcement and security officers in the United States. This book is offered as the basis for such a course of instruction. It is a "how-to,” self-study book for police and security officers, federal agencies, state police, county sheriffs, prison wardens and others — for anyone who wishes to improve their knowledge of secret inks. Covert inks are commonly used in espionage. It is not enough for a spy to obtain information; he has to send it to his organization, and this is the most dangerous part of his
work. Of all the spies who are captured, about ninety percent are caught, not in the process of obtaining information, but when they attempt to report it through their secret channels. Although codes are popular in secret service work, since they can express more in less space, long messages are always dangerous. Thus, there is a need for something like invisible ink, which gives the impression that no message at all has been sent. One of the most remarkable features of the world-wide clash of spies is their rivalry to concoct new and more effective covert inks. Many new inks have been discovered by such research. However, Israel is the only country that has made a systematic investigation of the covert ink phenomenon and now leads all others in this field.Ammonia Inks.
Appearing and Disappearing Inks.
Reagent Secret Inks.
Israel’s Secret Ink and Developers.
Temperature-Sensitive Inks.
Ultraviolet Inks.
Vapor Inks.
Vanishing Inks.
Poison Inks.
Incendiary and Pyrotechnic Inks.
Gamblers’ Secret Inks.
Luminous Inks.
Magic Trick Inks.
Water Inks.
Miscellaneous Inks and Papers.
Covert Pens.
Covert Mail Opening.
Chemical and Physical Data.