The Pigskin end.
(Continued from the Pinfeed end.)
After 1960, NCR paper mostly took over multipage business forms. NCR paper didn’t need machines at all.
One of my big themes: The best solutions come from improved materials and methods, NOT from new mechanisms or circuits or programs. Materials are the BIG story, damn near the ONLY story. Materials rarely get credit. All glory goes to inventors of machines and software.
In this case the exceptions are still fairly important, and Standard Register prospered from the exceptions. NCR paper has one major disadvantage. It never stops copying. After you’ve separated the top and bottom and stored the top in a file, the top copy will continue to smear whatever is under it. If you leave top and bottom glued, every touch on the top will make new confusing marks on the bottom. With interleaved carbons you can simply remove the carbon to prevent mess and confusion. Interleaved carbon sets are still easily available, and interleaved pinfeed forms are still common, especially in the self-folding envelopes that IRS sends out as W2 and W4 forms.
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NCR paper was invented in 1953, using ‘encapsulated’ ink on the back of the top sheet and reactive clay on the front of the bottom sheet. Pressure pops the capsules and releases the ink. Other versions used mutually reactive clay on both top and bottom.
These methods were based on techniques first developed for coating vitamin tablets. The key to all of the tricks is gelatin, ‘preferably from pigskin’.
Gelatin is the key to a WIDE variety of important industrial processes, known technically as coacervation. This youtube video shows how it happens. The guy is speaking Thai, but fortunately the containers are labeled in English.
He starts by stirring and heating water. He mixes in some gelatin and lets it get foamy. Then he adds ‘Acacia’, more familiarly Gum Arabic from tree sap. After more mixing, he gathers up the little capsules.
Those capsules can contain almost anything that needs to be held in a flexible distribution, then released or activated. In NCR paper the capsules contain ink. Substitute silver iodide and you’ve got photo film. Substitute sugar and you’ve got marshmallows.
Here’s an animation of how the capsules function in NCR paper. The coacervated gelatin film coats the bottom of the top paper. Pressure from a pen pops the capsules and spits the ink into the bottom paper.
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In part 3 I’ll generalize.
Polistra's Mill 