Lambda-Eyde - 21-6-2011 at 22:20
CIA declassified several recipies for making "invisible ink" a few months ago. Included are the attached documents and links to CIAs websites.
Hopefully some of you will find this interesting. 
Document 1
Document 2
Document 3
Document 4
Document 5
Document 6
Attachment: Secret-writing-document-one.pdf (447kB)
This file has been downloaded 366 times
Attachment: Secret-writing-document-five.pdf (438kB)
This file has been downloaded 320 times
Attachment: Secret-writing-document-six.pdf (1.5MB)
This file has been downloaded 340 times
Attachment: Secret-writing-document-three.pdf (427kB)
This file has been downloaded 322 times
Attachment: Secret-writing-document-two.pdf (1.1MB)
This file has been downloaded 445 times
[Edited on 22-6-2011 by Lambda-Eyde]