This image of opening between two of the parchment leaves (with paper guards in the center) shows the history of the binding and rebinding: the white stripe you see to the left of center is a wide stripe of abrasion that continues to the other side. This was definitely done after the image was made, and after the parchment was folded for binding, because where the pigment underneath is thicker, the skin was abraded more and actually bears the image of the pigment, just like a crayon rubbing of a gravestone. The dark brownish-yellow is the animal glue from the first binding, which was not removed for the rebinding. In the first binding, the guards were attached on the recto or the verso of each bifolio, with no apparent pattern; in the rebinding, they were only attached on the recto, so this glue was only visible on some of the bifolia prior to disbinding.

Because the extant materials were in poor condition and not the originals, and because the contents of this binding are so important, I decided to disbind the volume and rebind it with new, sympathetic materials that would better protect the charts. The first step was to remove all of the old guards and adhesive residue: the former was easy; the guards were mechanically torn off and the leftover paper thinned with a scalpel. The rebinding adhesive turned out to be a thin, slightly opaque white adhesive that I didn't identify and could have been one of several things. It responded to moisture, as did the animal glue, so with blotter inside the bifolia, once the adhesive was mechanically removed as much as possible, I used minimal poulticing with sodium carboxymethyl cellulose (SCMC) to take up the rest. I found that if the gel stayed on more than a few seconds, the red pigment offset slightly on the blotter---and upon closer inspection I could see that it had offset in the gutter of some bifolia during the previous rebinding as well, leaving a ghost impression on the other side of the fold. This made me wary of using more tradition water-based adhesives like gelatin, isinglass, or wheat paste to adhere new guards, but I'll talk about that more later.