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This business form, an absentee report, was (presumably) photo-typeset then photographed to produce a process negative. This is about the same as for production of a photoengraved plate.

The negative is then used to image a sheet of photo-sensitive polymer. In this case the polymer is coated onto a metal backplate, possibly of steel. After exposure, the polymer is washed out with the relevant fluid. For many types of polymer plain water is all that is needed. The plate is then mounted on a wooden block, type high.

As printers began to explore the use of phototypesetters and computer typesetters while still using letterpress printing, a cheap method of producing the relief printing surface became available in the form of photopolymer plates. These were much cheaper than regular photoengraving and could be produced in-house whereas the acid-based engraving process could not, except for the largest users like newspapers.

The Museum has thousands of photopolymer plates covering a very wide range of work. Many of them have deteriorated, some to the extent of the polymer peeling away from the backing. So not all can be printed now, but mostly they reveal the nature and details of the job.