The Ditto Machine
A spirit duplicator (also referred to as a Ditto machine ) was a low-volume printing method used mainly by schools and churches. The term "spirit duplicator" comes from the alternative term for alcohols, which is "spirits." Alcohols were a major component of the solvents used as "inks" in these machines. The spirit duplicator was invented in 1923 by Wilhelm Ritzerfeld. The best-known manufacturer in the United States was Ditto Corporation of Illinois, hence that name.
A ditto machine used a solvent like methylated spirits or ammonia to transfer ink from the master copy (the template, if you will) onto other pieces of paper.
The master copy was a smooth, waxy piece of paper which was thickly inked when printed. The procedure for printing on a master was like the reverse of a carbon-copy; instead of writing on the normal paper and having the carbon underneath, the text and pictures were printed onto carbon paper of varying colours to transfer print to the master. If you want to know exactly how thickly a master was inked, put your printer on the best quality and print about two or three passes onto the same sheet of paper (so that you are printing over the previous printing, I mean).
The master was then wrapped around a drum, and the solvent was applied as the drum rotated. The solvent either softened or melted the ink so that just enough of it would stick to the blank sheets of paper. A lot of the copies produced in this way came out with purple ink because purple “provided the best contrast” As you can see in the following photo Ditto copies were far from easy to read.
Both the isopropanol and the methanol found in ditto solvents are toxic substances. These chemicals can cause a host of medical problems when humans are improperly exposed. Material Safety Data Sheet (MSDS) guidelines recommend the use of personal protective equipment during exposure to methanol, however, most chemists work with methanol and isopropanol wearing only medical exam grade gloves, goggles and a working fume hood as the chief, no-ingested or inhaled reaction with methanol is limited skin irritation.
Ditto machines were popular in schools and churches as no electricity was needed to make quick stinky copies. Nothing smells quite like a fresh slightly wet Ditto copy.
They have gone the way of the typewriter and the dictaphone.
They Always Come Back:
Thanks to the efforts of this site they are not forgotten.