The stencil duplicator works by forcing ink through a stencil onto paper. Also called mimeographs they were often used for print short-run office work, classroom materials, and church bulletins. They eventually were supplanted by photocopying and cheap printing in the late 1960s. In developed countries photocopying and offset have replaced mimeography even though in mid-range quantities it remains more economical and energy efficient. In developing countries they are still often used due to the robust technology and the ability to be hand-cranked thus not requiring electricity.
Thomas Edison received a patent in 1876 for “Autographic Printing”. Albert Blake Dick coined the term when he licensed Edison’s patents in 1887. The term eventually became generic. The machines were created independently in Britain and were often called “duplicators”. In 1891 the first rotary machines were created and they created faster reproductions since the pages were produced and moved by rollers instead of pressing one single sheet at a time.
Single drum machine and dual drum machine are the two types of mimeographs that came into use by the 1900s. The single-drum used a single drum for ink transfer to the stencil while dual drum uses two drums. The single drum could do multi-color work by changing the drum to that of each color needed.
Due to it being cheaper and requiring no skill the mimeograph became popular. The stencil is wrapped around the ink drum then a piece of paper is drawn between the rotating drum and a pressure roller. Ink is forced through the holes on the stencil onto the paper.
Any mistakes can be corrected by brushing them out with correction fluid and retyping once it has dried.
There are still companies that make and sell highly automated mimeograph-like machines that are similar to photocopiers. The modern version contains a scanner, a thermal head for stencil cutting, and a large roll of stencil material inside the unit. It can make the stencil and mount them to the print drum automatically. The Risograph is the best known of these machines.
The mimeograph was used to created letters and symbols that made illustrations and art.