German Secret Ink (Declassified)
6/14/1918
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This document is a copy of the formulas used in preparation of German secret ink.
Additional details from our exhibits and publications
For 95 years, a small number of documents related to invisible ink have been national security-classified material and unavailable to the public. Believed to have been the oldest documents still classified by the United States, they detail German secret ink formulas developed during World War I. This document is a copy of the formulas, written in French with English translation, used in preparation of German secret ink. The documents were declassified as part of the work of the National Declassification Center (NDC). The Center was established within the National Archives at the direction of President Barack Obama in late 2009 with the mandate to review more than 400 million pages of classified records by the end of December 2013.
This primary source comes from the Records of the Office of the Chief of Naval Operations.
National Archives Identifier: 5890789
Full Citation: German Secret Ink (Declassified); 6/14/1918; File 20961:174; Confidential Suspect and General Correspondence Files, 1913 - 1924; Records of the Office of the Chief of Naval Operations, Record Group 38; National Archives at College Park, College Park, MD. [Online Version, https://www.docsteach.org/documents/document/1-german-secret-ink-declassified, December 5, 2019]Rights: Public Domain, Free of Known Copyright Restrictions. Learn more on our privacy and legal page.