Hectographs

A hectograph is a duplicator that uses a gelatin-based pad to transfer ink from a master copy onto multiple sheets of paper. It was a popular method of reproducing documents before the widespread adoption of photocopiers and mimeograph machines. The process typically involves writing or typing on special hectograph paper with a carbon-based ink, which then transfers to the gelatin pad. Subsequent sheets of plain paper pressed onto the pad absorb the ink, creating a duplicate.

The invention of the hectograph is often attributed to Moritz von Rohr in the late 19th century, though similar principles may have been explored earlier. Different formulations of the gelatin pad existed, with some using glycerin and others using a combination of ingredients to achieve the desired consistency and ink absorption properties. Hectographs were particularly useful for small print runs in schools, offices, and for personal use due to their relatively low cost and simplicity. The quality of the duplicates could vary, often appearing somewhat faded or smudged compared to the original. The ink used was typically aniline dye-based.

The lifespan of a hectograph pad was limited, and it would eventually become saturated with ink and lose its ability to produce clear copies. The pad could often be cleaned or reconditioned, but eventually, it would need to be replaced. While largely obsolete today, the hectograph represents an important step in the history of duplication technology.