A scrap book, which was extremely important for the archives, was brought to our lab for treatment and preservation. The data and photographs were important and these original records need to be rescued from further deterioration.
The pictures, maps and documents in this scrapbook were pasted with an acidic glue to the black paper of a photo album. The acidic nature of glue could be confirmed by simple observations. The glue had turned dark brown and had transferred this stain as well acidic character to the paper on which it was applied. The album’s black paper had also tuned brittle because of its inherent acidity.
Apart from the acidic glue and paper, there was glassine separating sheet between all pages of the album. This glassine had also tuned brittle because of ageing. Moreover, it had stuck to the front of many photographs it was in contact with.
Considering the acidic nature of the paper and glue, it was considered urgent to detach all original photographs, maps and documents from the acidic paper and also to remove the glue at the back of all these originals. These two tasks are not as easy as they seem. More so, because of the age of the originals and the way they were completely and strongly adhered to the paper.
Various, safe humidifying techniques were used to carry out this intricate job. Some level of humidity was required to soften the glue. But, this had to be done without damaging the moisture sensitive photographic material and the inks used on the maps and documents. Even the mild and slow humidification through swins (polyester web with a polyurethane membrane) was found damaging after a point. So, we calculated the exact time for which the humidification could be provided in a controlled manner and under constant supervision.
All the photographs, maps and documents that were pasted with acidic glue were removed from the brittle black paper. The remnants of the glue were removed from the back soon after the detachment because if they were left even for a couple of minutes, the glue would dry and become too hard to be removed. So, it had to be cleaned or removed when it was still soft after the process of detachment.
The photographs with glassine stuck on their front had to be treated very carefully to remove the glassine. We could see the sticky gluey material that had embedded the glassine in the image layer of the photograph.
After cleaning all the originals, we flattened them without using humidity.
The originals were then fixed on new acid-free thick paper with the help of conservation grade polyester corners without using any glue.
A special box with thick acid-free board was constructed. It was given a base of ethofoam sheet for cushioning the heavier new album. Volume of the air inside the box was calculated and accordingly, sufficient number of humidity regulating sheets were installed. A temperature humidity datalogger was also installed inside the box. Its readings were checked after a few days to compare its working before keeping in the controlled micro-environment and after. According to its readings the humidity was being kept in control with the help of humidity regulating sheets. But the datalogger had stopped recording as its memory was full. It was found that in the default settings it was recording each and every second and its maximum capacity is 43000 readings. So, datalogger was taken out and set for longer intervals of time of reading. It was again kept for some days in uncontrolled environment to see how the graph shows up with this new setting and then for last few days in the lab it was again put in the box with controlled micro-environment.