I posted some photos a while ago of this 1616 bible before treatment—it's so badly damaged that the treatment will need to be in stages: first the paper will be repaired, so that I can see what if anything needs to be done about the binding itself. And by cleaning and repairing the paper, I'll end up spending a lot of quality time with the book, see how it moves, where there might be weaknesses in the binding, etc. I started at the front because after the first section the paper tended to be folded/wrinkled/curled in a way that it would be easier to work from that direction. It is also very much more damaged towards the back, so it would buy me some time think about how to approach it! Concurrently, because of time, we're stabilizing the furniture beetle-damaged front board, so you may notice in some of the pictures that the leather has been taken off the board—but that's a subject for another day.
At both the very beginning and end of the book, as well as a few small parts throughout, there are missing (torn out) leaves. The paper that remains, except for that at the back, is in pretty good condition physically—I've just been working on a different book that was so water-damaged the paper almost felt like a pile of fibers, that couldn't even be brushed for a clean because so many of the fibers would fly away with each swipe of the brush. There are stains and tears and in some places, a lot of accumulated surface dirt, but it was quality handmade paper and is still quite flexible and robust considering. In some places in this book there is just a corner (at the tail/fore-edge) missing, but a lot of leaves have many more tears and losses. If every leaf was missing the same amount of corner, roughly, I could have stabilized the edge but left it as-is—but every once in a while, there was a corner that was still there, just folded up quite tightly. If I unfolded it next to a lot of missing corners, it would be vulnerable and become damaged in the same way as the others. And so I am making up for all the missing paper with new, long-fibered Japanese kozo papers, until the leaf was a rectangle again. I've just gotten to the title page of the New Testament—and then the real fun begins, as the damage gets worse and worse from there.
The first step is to gently unfold any edges that are folded over—I do this with a PTFE folder, holding each fold as it is opened for a few seconds to teach it to stay flat. The really damaged edges feel more soft where the fibers have been weakened by too much creasing or, in some cases, by water damage that affected the sizing, so over those areas I paste a very thin kozo tissue, thin enough to read through but enough to give the paper a little more support. Then, with thicker kozo paper, I trace the edge of the tear using a water brush. When the paper is wet, it can be torn easily and without breaking the fibers. I'm using a variety of weights depending on how big the area of loss and how robust the paper to which it will be attached. I work through a section, with blotter and a spun-bonded polyester sheet (that the paste won't stick to) in between each leaf. When they're dry, I separate them from the polyester, and trim the edges of the new paper fills with a sharp knife.