Methylcellulose (or methyl cellulose) is a chemical compound derived from cellulose¹. A white powder that dissolves in cold (but not in hot) water [unlike gelatine], forming a clear viscous solution or gel. It is sold under a variety of trade names like Citrucel® and is used as a thickener and emulsifier in various food and cosmetic products, and also as a treatment of constipation². Like cellulose, it is not digestible, not toxic, and not allergenic. And it is also the main ingredient in K-Y Jelly® and artificial tears and is used in the porn industry as artificial semen . . . but enough about my private life.
Methylcellulose is also employed as a mild glue which can be reversed with water. Methylcellulose is the main ingredient in many wallpaper pastes³ (the other ingredient is wheat starch). There you have it. It’s sticky when wet, it dries, and get’s sticky again when rewet. It isn’t strong enough for spine work, but works plenty well for paper repairs. Wheat starch paste is use much more by conservators and binders, but that requires cooking and has a short shelf life.
RECIPE: Stir 1 rounded tablespoon methylcellulose into 1/2 cup distilled water. Let stand and thin with water if necessary. Acid-free, non-toxic, odorless and vermin-proof.
¹ A complex carbohydrate, (C6H10O5)n, that is composed of glucose units, forms the main constituent of the cell wall in most plants, and is important in the manufacture of numerous products, such as paper, textiles, pharmaceuticals, and explosives.
² When eaten, methylcellulose is not absorbed by the intestines but passes through the digestive tract undisturbed. It is used to treat constipation, diverticulosis, hemorrhoids, irritable bowel syndrome and diarrhea. go figure.
³ When the book isn’t particularly valuable or I don’t actually HAVE any methyl cellulose on hand, I reach for the wallpaper paste and mix it VERY well and very thin.