About 11 days into printing, with me on press for about eight of those days, for three to nine hours per session, I’ve hit some walls. The printing is still going well (I'm about half done with the black passes), but I’m discovering the limitations of printing large pages with fine type on an old proof press.
Before I get into details, here’s a time-lapse recording I made of several hours of printing the other day. It’s pretty cool! My friend Jeff Carlson came in and shot a ton of photos a week ago Saturday, and I should be able to share some of those with you, too.
A proof press runs rollers over type following by pressing paper in a continues line across print surfaces. On a platen (or clamshell) press and similar full-impression presses, pressure is distributed simultaneously between the entire print area and paper. A proof press can be dialed in fairly precisely, but the nature of the beast makes it more likely you can see variation both from across the direction of printing and with the direction of printing.
After some erratic results, my mentor suggested that the heat from outside (the press has a bank of windows facing south) and the continued use of the ink rollers over the course of a day could easily result in warping. Uneven ink rollers, bulging in the middle or flaring to the ends, results in uneven inking, which results in uneven printing. I'll likely limit my on-press time with black ink to a single pass (about three hours) instead of two per day to avoid this, since temperatures are heating up. The press is air conditioned, but that doesn't mean it's perfectly cooled.
The more general problem is that it's very difficult to keep a consistent page color and ink color over long runs. One of the press sheets I just finished (side 9 of 16 with black) I’m rethinking—I think its opposite side is too gray relative to other pages printed and the side I just printed. I may wind up re-doing both sides for consistency. I knew this might happen, and I have plenty of paper to do so. It adds about six or so hours to printing time, but it's critical that the black all be roughly the same, or it’s extremely noticeable. I have to look at it again in good light.
The second color pass for illustrations and the third color for chapter numbers are much more straightforward: less area covered, not intended to be legible in the same way as the black text, and easier to set up and print.
This is all a learning experience. I've put more time in on a press in the last two weeks than in the last six months, and every day I learn new tricks and insight. I want to make the best book I can, but I also recognize that in learning as I go, I’ll find I could have done something better, and have to consider whether I proceed or go back. In general, everything looks good, and the photopolymer plates and the press are performing well. I just have to keep working on being able to tune the press as I go and its conditions change even over the course of a run.
For instance, here's a funny problem. The tympan is the smooth paper that covers the drum over which you stretch the paper and roll it onto the printed surface. The tympan sheet is screwed in one end and stretched on a bar with a ratchet on the other to keep it tight—like a drum! It literally should made a drum-like sound when tapped if it's in correctly. Under the tympan, between it and the metal of the roller, you put flat packing material to raise the paper you’re printing on to just touch the printed surface when it's rolled over it. (Or, in some cases, to make a deeper impression, a noticeable debossing.)
Because I'm printing so much and printing on a sheet of photopolymer, which really grabs the paper and pushes against the tympan, the packing material slips over time. My mentor noticed this at one point, and she caught it before it shifted enough that the paper wasn't making an impression against the bottom of the plate! So every 100 sheets or so, I have to disassemble the tympan, get the packing back in order, and tighten the whole thing back up.
Unrelated, it’s lovely working in the just-north-of-South-Lake-Union district of Seattle. On the edge of its history, in the middle of change, in a beautifully arrayed building, in a perfect letterpress shop, with wonderful people on staff and in the school's community. Everything is in flux: an old building one day is a pit the next and a skyscraper seemingly the day after that. But then a tree appears in the glass jungle.