"THE SOCIETY FOR THE EXPLORATION OF CONFIDENTIAL ENVELOPE TINTS
We are a playful collective of Obscurationists: amateur pattern-hunters, whimsical archivists, and curious minds united by one thing β wanting to learn all about security envelope patterns.
You know, those prints inside your bills the average person doesnβt think twice about? We think about them all the time."
https://secret-archive.org/the-archive/