Unknown Substances is composed of photographs from U.S. government files pertaining to unidentified flying objects. The photographs and documents were obtained from U.S. Air Force files in the National Archives as well as Freedom of Information Act requests submitted to the CIA, FBI, and NSA. A process of bureaucratic accumulation and circulation has abstracted the declassified pictures. They have been rendered unintelligible through repeated photocopying and transfer to microfilm during their time in the archives. There are also photographs that appear to be deliberately concealed. Rather than functioning as reliable evidence, the pictures do not conform to conventional epistemic expectations of photography. These photographs become a point of departure for grappling with the limits of photographic legibility and representation when reproduced at large scale, recalling the negation of modernist abstraction and collage. The aesthetics of obfuscation and concealment allow for the images to be opened up to multiple interpretations while also embodying anxiety over excessive government secrecy and information that remains inaccessible.