If you went to school in the United States before the 1980s, you know a smell that no longer exists anywhere in working life. It was sweet and sharp at once, faintly chemical, and it came off a sheet of paper that had just been handed to you, slightly damp, printed in a purple unlike any purple a real printer would make. The machine that produced it was called a spirit duplicator. Almost everyone called it a ditto machine.
The mechanism was clever and a little strange. You created a master by typing or drawing onto a sheet backed with a special carbon paper loaded with aniline dye. Crucially, you typed in mirror image, because the dye side faced the drum and the words had to come out the right way round on the copy. The master was then clamped to a rotating drum. As each sheet of blank paper passed through, a small amount of alcohol-based fluid was applied, dissolving a little of the dye and transferring it onto the page. The alcohol evaporated almost immediately. That evaporation is the smell.
Each pass wore the master down. Depending on the master and the dye, you could get a few dozen to a couple of hundred readable copies before the purple faded into a ghost. Teachers learned to judge how close they were to the limit, and the last students in a large class sometimes received a sheet that was barely legible. It was a technology of scarcity that everyone in the room understood without being told, and it gave the classroom a small, shared economy of who got a clean copy and who did not.
The ditto machine is often confused with the mimeograph, and they are not the same thing. The mimeograph, associated with the A.B. Dick company and with Thomas Edison's early work on stencil duplication, used a cut stencil and conventional ink rather than a dye master and alcohol. The ditto, or spirit duplicator, was a separate invention, developed in the early 1920s, and it is the one that produced the purple pages and the smell. "Ditto" was also a brand name, and it became a verb: to ditto something was to run it off in copies, and students used the same word to mean agreement, a piece of borrowed language that quietly outlived the machine that inspired it.
The sound of the machine was part of it, too. There was a soft, wet, rhythmic turning as the drum swept each sheet through the fluid, and the smell got stronger the more you printed. A teacher making enough copies for five classes would work the handle for twenty minutes, and the room would carry the scent for the rest of the afternoon. It is one of the few school experiences of that era that nobody describes by what they learned, only by what the air was like.
What ended it was not a single moment but a slow overtaking. The photocopier, commercialised in the late 1950s, could copy anything already printed, in plain black, without a master or a drum or a fluid, and it did not fade. Offices switched first, then schools. The ditto machine survived longest where budgets were tight and the volume was low, and then it was gone.
It is worth being precise about what was lost, because it is not the copies. The copies were bad. What was lost is harder to name: a colour, a smell, the particular experience of a page still warm from the machine and handed to you one at a time by someone who had made it specially for your class. Almost every technology that disappears takes with it a sensory signature that no replacement bothers to reproduce, and that signature turns out to be the part people actually remember. Nobody misses the faded type. A great many people, given the right cue, can still smell the room.
The photocopier won for reasons that had nothing to do with sentiment, and that is the ordinary way these changes happen. It was cleaner, faster, and did not require anyone to retype a document in mirror image on special paper. The ditto had one advantage, and it was the one that could not be argued on a spec sheet: the master was cheap enough that a teacher could make one for a single lesson and throw it away without a thought. You did not have to decide that a worksheet was worth preserving forever. You could make twenty copies for one afternoon and let it go, and there was a freedom in that, a willingness to waste a little that the new machines quietly took away.
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