The spirit duplicator, also known as a ditto machine, was used to make copies of documents before the modern photocopier was widely available from the 1980s onwards.
Invented in 1923 by Wilhelm Ritzerfeld, ditto machines were popular among schools, churches and clubs for making copies of worksheets, flyers, and so on.
To use the machine, a special master copy had to be created on paper with a waxy ink on the back that would dissolve in alcohol.
The master copy was then attached to the drum of the ditto machine, and multiple copies could be made by turning a crank that rolled the drum over the paper.
The quality of copies depended on many factors, including the quality of the master sheet and the type of paper used, and the number of copies was typically 50 to 500.
Ditto machines fell out of use as photocopiers became more common but have a legacy as a duplication machine of choice for smaller organisations.
