I’m an associate editor at The Atlantic. On Twitter, I’m @yayitsrob.
The hectograph — or jellygraph — was a near-print process used in the late 19th and early 20th centuries. It could make cheap copies of original documents, usually for business or professional purposes, by transferring the image of the original to a gelatin bed with colored dye. Copies could then be made from the bed as long as the dye lasted.
Says Wikipedia: “At least eight different colors of hectographic ink were available at one time, but purple was the most popular because of its density and contrast.”
I use my Tumblr like a combination of a hectograph, a commonplace book, and a wunderkammer.