Castle made his art with found paper such as newspapers, magazines, catalogues, food packaging, matchboxes, calendars, and, most charmingly, his niece’s homework, which he collected during his daily scouring of the family home.
Castle also developed his own media, fashioning “ink” out of soot his scraped from a woodstove and mixed with his saliva, and using colors he leached from materials such as crepe paper. Although Castle was geographically isolated and did not pursue formal artistic training, these materials demonstrate his steady exposure to mainstream culture beginning in childhood when his parents served as postmasters of Garden Valley. As he developed his art, mass mailings and other print sources provided Castle with a window on the world, examples of design, and the materials to create.
Because Castle left his works undated, the age of the papers he employed offers one of the only clues to the date of a given piece. Even so, this establishes only the earliest possible date of execution, leaving most works untethered across a span of decades.