I recently got a small diary in the lab that had been previously repaired. Instead of simply joining the split pages together with a thin strip of tissue, they opted to line the entire two-page folio with heat set tissue.
Dealing with prior repairs is always a conundrum for conservators. With time and resources limited do you leave old repairs if they are still working (even if they are really ugly), or do you replace them with more sympathetic and reversible repairs? As in all things conservation it depends.
In this instance I removed the old repairs because they were difficult to read through. Luckily, whoever lined the pages with heat-set tissue didn’t use a hot enough iron so the tissue didn’t attach well to the pages. Lucky for me because if they did use a hot iron, soaking in a solvent would have been my only recourse to remove the lining. I was able to simply peel off the old tissue (image left) and replace it with smaller strips of Japanese tissue adhered with wheat starch paste (image right).
The pages look much better and you can read them without the distraction of the all-over tissue lining. I feel like I got away easy this time.