William Abel, a mail censor at Iowa's State Prison, Fort Madison, using a hot iron to bring out a secret message written in lemon juice on a letter.Three Lions/Getty Images Humans have had a long ...

The secret history of invisible ink. American Expeditionary Forces secret ink lab By signing up, you confirm that you are over the age of 16 and agree to receive occasional promotional offers for ...

Readers of a certain age will remember those 'invisible ink' spy toys that let you write a 'secret' message which would only appear after rubbing the page with half of a lemon. Yeah, this is not that.

This work is an experimental documentary animation by the traditional Japanese technique of ABURIDASHI And its consists of three parts Beginning Middle and End Beginning is a personal video made to ...