On Monday I asked the team what kind of paper size they typically use on weakened paper in the collection. I received several replies, some said Methyl cellulose, others said Klucel G, diluted paste was mentioned as well as gelatin. A seemingly simple question sparked a little research and a mini-experiment of my own.
I decided to take a laid paper commonly used here (Moulin du Verger) and test seven different sizes to see their differences. The following sizes were tested:
- Gelatin (1% solution)
- Klucel G (1% in IMS)
- Diluted EVA (1% in water)
- Methyl cellulose (1% solution)
- Methyl cellulose medium viscosity (1% solution)
- Jin Shofu wheat starch paste (diluted after cooking)
- Wheat starch paste (diluted after cooking)
All of the sizes except diluted EVA (I believe I diluted the EVA too much the test piece felt no different from the unsized paper) gave additional strength without causing much color change. Of the seven gelatin, Klucel G, and both types of Methyl cellulose gave the best results; giving strength, minimal color change and not causing the paper to curl. The Jin Shofu and ordinary wheat starch paste pieces have curled, a problem that could be solved by sizing the other side of the paper.
After my little test I have to say that of the seven I preferred gelatin. Honestly, I was expecting Klucel G to be my favorite as it has been my size of choice for some time. It dries quickly, causes minimal color change and gives an ample amount of additional strength to weakened paper. Gelatin does all of the same things, however I preferred the feel of the gelatin sized paper to the Klucel sized paper.
My personal opinions aside, every paper is different, some have extensive mold damage, dirt or simply soft areas caused by heavy use. As is usually the case in conservation there is no standard answer, every item is individual and will react in a different way. At least now I have a greater understanding of my options and will be able to make informed decisions based on what I have learned.