Keeping stuff: How to preserve course papers despite technological change

Dittos

I began teaching in 1976, at Arizona State University. As a teacher, I had to create handouts, syllabuses, exercises, and examinations in a form that could be copied easily and inexpensively. Although by this time photocopying was fairly common, it was also fairly expensive -- copying a two-page handout for twenty-five students might have cost the equivalent of ten or twelve 2009 dollars. So we actually used dittos (that is, mimeographs) instead.

To prepare a ditto, we used a two-layer form. The top layer was paper; the bottom one was a sheet coated with ink that would stick to the back of the top layer wherever pressure was applied, by a typewriter key or the tip of a ball-point pen. We typed or wrote the text onto the top layer. When the layers were separated, the text appeared in sticky ink, reversed, on the back of the top layer. We then mounted this form, ink side out, on a rotating drum that applied it to one blank sheet after another, supplying additional and more fluid ink, with the result that each blank sheet wound up with a doubly reversed copy of the text.

Here is a dittoed handout from my first year of teaching. In the original, the type is blurry and dark blue, corresponding to the color of the fluid ink that the ditto machine used. This ink has faded noticeably, but the document is still readable. Many of the letters are incomplete or filled in, a distortion that is the result of the inaccurate transfer of ink from the bottom layer of the two-part form to the top layer.

Although it was possible, if you were careful, to recover the top layer of the form after copies had been made from it, file it, and use it again later, I never did this, but simply retyped anything that I needed to re-use.