Perfecting, with the accent on the second syllable — perfēcting, must have been a phenomenal break-through in productivity when it was first introduced. Prior to this every sheet would go through the press twice; once for the first side and then once for the second. The sheets would be stacked off after the first side had been run, then taken round to the other end of the press, loaded upside down (and importantly right way round) and run through again after a different form of type had been made-ready.

When was perfecting invented? The Oxford English Dictionary has a reference to its meaning in our sense dating from 1824:  “When one side is printed, it revolves from one cylinder to the other, and is then perfected by the second form”. The definition from William Savage’s A Dictionary of the Art of Printing (1882-3) suggests that the name might first have applied to the printing of the second side of the sheet regardless of whether it was done in one pass or not: “Printing the second form of a sheet; called also working the reiteration.” Maybe the origin of the word is just the obvious one: to make a sheet printed on one side only perfect, you’d have to print the other side!

Perfecting is achieved by one of two means. Either the press perfects using two units, with the sheet being turned over between them; or it perfects “blanket to blanket”. 220px-Offset.svgThe diagram shows a single unit, non-perfecting, offset press. Imagine the top half, above the paper, duplicated and reversed below the paper. Then the two offset cylinders (carrying the blanket onto which the inked image has been offset from the plate) come together with the paper between them. The two offset cylinders supply their own pressure to pick up the image on both sides of the sheet simultaneously. For a convertible perfector you need to imagine a duplicate of the diagram placed next to the first one, with an arrangement of conical rollers between them to flip the sheet (or of course the web) over. One advantage of the transfer cylinder arrangement would be a gain in flexibility. The printer could use such a press to perfect in one color, or to print a two-color job in non-perfecting mode.

Miehle 60 x 40 sheetfed letterpress perfector at Jarrolds, Norwich

Miehle 60 x 40 sheetfed letterpress perfector at Jarrolds of Norwich

The two-unit method would of course have to be the mode used in letterpress printing: just try mounting a form of metal type upside down so it could perfect simultaneously. Furthermore letterpress requires much more pressure to transfer the ink than does offset lithography: pressure which just would not be available without an impression cylinder arrangement. However letterpress printing had evolved a rotary press in 1843, using a flexible plate made from a mould of the type, and the first perfecting web press was introduced in 1856. Assuming all these dates are accurate, one can envisage a development as follows: sheet fed letterpress printing one side only from c.1450 till 1824; 1824 perfecting using two units; 1843 rotary press; 1856 perfecting web-fed rotary press. The first offset press for printing on paper wasn’t introduced till 1904.

When I started in book production the majority of the books we did were printed by letterpress, from type, on single unit presses, without perfecting. Although we modern folks are inclined to assume that efficiencies in manufacturing will always triumph, we need to recognize that an installed base of less efficient equipment may be a much better business solution that rapid investment in the latest kit. Also, efficiencies in manufacturing become more important the longer your print runs. The sort of books I was involved with did not have long runs, so the efficiencies of perfecting were not so significant that one needed to go in quest of them.