Invisible ink

Journal entry

 * Invisible ink


 * Those wishing to conceal the true contents of their missives from third parties often resort to penning their letters with invisible ink. A message set down in this manner becomes visible only when the document is treated with a substance that reveals the writing.


 * Some use invisible ink as a dye, soaking entire pages in it instead of using it to write. The recipient of a message thus treated can confirm its authenticity by applying a substance that will turn the page a specific color, usually blue.