One important resource for mimeograph revivalists is the patents associated with all aspects of the technology. The patents allow us to see how the earliest versions of duplicating machines were designed and what supplies or materials were used; later patents allow us to understand where processes were streamlined and what materials came into use as people experimented and tinkered.
Not every duplicator-related patent is of use – some merely reflect a change in machine specifications, for example in paper-feed mechanisms, or in the use of newly-invented chemicals and their processes; however some reveal game-changing modifications or give clues to ways we can retro-innovate and simplify our materials in order to inscribe a less global radius around all the parts that have to be sourced.
Examples of this type of patent-as-resource are easily spotted among the patents for stencils. Currently, traditional coated-paper stencils are difficult, if not impossible, to come by unless you happen to score a time-capsuled stash on ebay or have access to Daisho products in Japan. Modern tattoo stencils and their Riso counterpart (Riso master rolls) are manufactured in East Asia (China and Japan only, as far as I can tell). [For more on stencils, please see this blog post. – coming soon]
This section is unlikely to contain every patent related to non-digital duplicating machines and processes; however, the intention is to provide a general overview and a decent selection of the many ways duplicating was accomplished, with a preference toward the low(er)-tech end of the spectrum.
For ease of use, this is separated into the following categories (subject to revision): stencils, inks, carbon paper and associated methods, hectographs, duplicating machines and their mechanisms.