How was a plate put on the press?

A simple question, but the practicalities that make up the answer are not so straightforward. Alan Druce had a go at explaining how the plate would be held on the printing bed (see page 332 onwards), though as he intimates, we don't actually know what the procedure was. We can only surmise.

Alan assumed that the purchase of some steel bar in addition to the metalwork needed for plate production would have been used to keep the plate positioned on the press. In practice, I am not sure that I follow Alan's reasoning as to how this would have been achieved. He does not say how the bar be attached to the press bed, and his point about the bar being above the level of the printing plate does not seem to be an aid for the printer. Where I sharply disagree is the suggestion that “an indentation or groove must have been cut into the roller” (p340). That would effectively mean that each press would be limited to one plate. Sorry Alan, I don’t buy it. There are in any case other uses for the bar, for example for production of dies or small plates for Perkins Bacon's other business customers.

Let's go through the procedure for setting up a brand new plate.

The steel plate would have initially been delivered ready to use, that is perfectly squared off with front and back parallel with each other and the edges square with these faces. At least the front would have been planed perfectly smooth. The steel would have been soft. Anything that did not conform to this list would have received some attention from PB's own engineers. This would have been a perfect place to start to allow the engraver to engrave the plate.

Once the plate had been completed it would have been hardened, and it's here that problems could start to emerge. The process of heating up the plate and then a staggered quench could introduce irregularities in the plate, specifically it could lose its squareness (if that is a word!). The plate may have twisted or bowed, one corner may have lifted or dropped or any combination of these faults. Would this matter? Well, yes. The plate had to sit flat and stable on the printing bed of the press as it would be travelling under the D shaped roller under quite a bit of pressure. It could not be allowed to wobble.

One solution would have been to plane or file the back of the plate flat so that it sat flush. But steel was expensive. The front of the plate would have to be planed at some point in the future (when the new impressions had worn beyond repair) which would remove metal, to do so from both sides would effectively double the rate of metal loss – halving the plate life. A less destructive answer would be to add shims under the plate to stop any rocking on the bed of the press. It was usual for printers using other forms of printing (e.g. typeface printing) to use sheets of paper to stabilise the print base (making up or decoupage etc), so this would have been familiar to them.

However, there is a problem. The printing plates had to be removed from the presses at the end of each day and placed in a safe cabinet under duel control. How would they have repositioned the plates exactly in the same position each morning? This is where Alan’s idea comes in with his suggested use of steel bar, in a similar way to how printers lock in place letterpress plates. However, there is no need for this arrangement with intaglio printing as all impressions come as a single piece. All that has to be achieved is that the plate be held in position on the bed of the press, with the facility to take the press off and replace it in exactly the same place as needed.

My imagination suggests two possible solutions to this problem.

1). Two bars of metal (cheap iron would do) drilled to take two bolts, was secured to the press bed through slanting slots drilled into that bed. Once the perfect position were found for the plate, the bars could have been cinched into position using two nuts below the press bed which would effectively lock the bar in position. With one bar locked at the base of the plate providing the horizontal alignment, the second bar would be positioned to the side to provide the vertical alignment. These two bars would remain in place semi-permanently until the plate was changed for another.

First thing in the morning, the plate was placed on the printing bed and aligned with the two locked bars. A third temporary bar could then be tightened against the third side using one or two wing nuts to hold the plate in place for the rest of the day. At the end of the day, only this one bar was loosened to allow for the plate to be removed from press and placed in the safe.

2). To have two vertical slots in the press bed, a known distance apart. The back of the printing plate would have had four holes drilled and tapped, the same distance apart. When positioned correctly on the plate, bolts could have been passed through the back of the press bed and screwed into the holes in the back of the plate. Then apply a washer, spring washer and wing nut to the bolt and tighten. This would have been a five minutes job. I am not sure I like this option, as it effectively makes the plate one sided. Perkins Bacon would have wanted to get the last drop of value from their expensive steel purchases.

As an added refinement for either option, a bolt could be fitted into a drilled hole at one corner of the bed and welded in place. This could act as a very secure initial point to lever the plate against, both at the initial setting up and during the morning setting up. In all cases, any bar or bolt appearing above the press bed would have been under the surface of the printing plate. So probably protruding no more than ¾ of an inch.

Update to my imagination (May 21)

I am looking into Neale's steam press at the moment and a diagram of the machine shows the plates being held in a frame. When I wrote the above piece I half had in mind that the plates would have been bolted directly to the chain that moved around the steam press. This not being the case, I am sure that the most probable scenario is solution 1 above.

Back in the real world

You may be thinking that the surviving press on show at the British Library does not have any holes or slots cut into the press bed, it is a plain polished piece of metal. True, however this press is something of a chimera, which has been made up of parts from different printing presses. We know that the presses used by Perkins Bacon had holes cut through them to allow for a gas burner directly under the printing plate. I do not see any difficulty in having other slots or holes being present in the press bed.

How did the printers make sure that the paper shim stayed in place. Leaving the paper loose on the press bed would not have been a solution as it would have quickly been worn or even torn. It was common for printers to paste layers of thin paper together to arrive at the correct thickness of shim required. An elegant solution would have been to paste the paper directly to the rear of the printing plate when the right thickness had been found. This could have easily been scraped off when the plate was removed from press for defacement.

An interesting side point here: they probably did not use traditional hide glue for this application, as you can reactivate hide glue by heating it (remember those old glue pots?). As the plate needed to be heated, the glue would have softened and have made a right old mess by the end of the day, sticking the plate, the paper shim and the press bed into one sticky lump.

AP

March - May 2021