Condition of the Victorian Glassine paper repairs
The survey revealed that glassine used as a paper repair material at the time of the 1874 rebinding was not aging well. Discolouration and embrittlement indicated that acid deterioration was in progress within the chemistry of the paper – at a molecular level a by-product of paper deterioration is acid. Acid is also a cause of deterioration, the process is therefore cumulative and accelerating – Any Tudor paper in close proximity to the glassine showed similar discolouration. Removal of the glassine was thought to be important if it was possible.
The adhesive was starch based and therefore soluble in water. However, the Tudor paper under the glassine was already mould and water damaged (which is why the glassine was applied in the first place) and was therefore very soft and extremely vulnerable to water.
Various aqueous poulticing methods were trialled including prefabricated enzyme poultice Albertina-Kompresse. All worked to a certain degree but all carried what was felt to be unacceptable risk to this particular paper. All aqueous treatments trialled were found to carry unacceptable risk to both the text and substrate, causing losses to both.
The Volume was put away in a dark cupboard in the conservation studio to await inspiration.
After a few weeks it was brought out again and I noticed that some of the glassine was auto-delaminating, blistering and lifting from the substrate. Apart from some Iron Gall Ink offsetting, the blisters appeared to have lifted cleanly. Maybe this auto-delaminating was being caused by changes in temperature and or humidity? I could think of no other cause.
The temperature and humidity in The Repository was typically 45-50rh and 17c
The temperature and humidity in conservation was typically 30rh and 22c
Were these very different conditions causing the auto-delamination?
Being hydrophilic, all paper tends to equalise with the humidity of the environment in which it rests, but these two very different types of paper, Tudor hand made rag paper and Victorian Glassine would certainly swell and contract at very different rates under fluctuating temp/rh. Perhaps this difference was causing stresses at the interface between the papers, causing the adhesive to sheer and fail. I decided to repeat the humidity and temperature cycling process a few times times by placing the volume in The Repository and the back in Conservation for a few weeks.
The blisters appearing in the interface between the Tudor rag paper and the Glassine were found to be increasing, and work started on removing as much glassine as possible without causing losses to text or substrate. About 80percent came away in this way. The remaining 20percent may respond to further cycling, Only time will tell.