Making your own parchment glue
In the Middle Ages, parchment glue was one of the binding agents for colours used in book illumination.This glue was made by cutting pieces of parchment into shreds and boiling them. This produced a gelatine that yielded a very pale, almost transparent glue with a certain flexibility and an excellent binding agent for the colours. According to D.V. Thompson (1), it was mainly the blue colours that gained their lustre through the use of size or gelatine-based glue. The blue colours were often applied a little thicker, and for this purpose, clarified egg white was too weak as a binding agent. Some medieval illuminators insisted on using gelatine made from the scrapings released during the processing of the skin/parchment they were painting on. They believed it was beneficial if there was a connection between the two materials. Sometimes, cartilage and tendons were also cooked along with the parchment. The result was an adhesive solution that formed a jelly when cooled. This jelly was cut into pieces and, after drying, the pieces had an unlimited shelf life.
Parchment glue mixed with lead white was also used as an undercoat to paint the miniatures on.
Before rabbit skin glue emerged in the 19th century, parchment glue was also used for preparing painting canvas. The glue is slightly yellowish and does have a lower adhesive strength than Isinglass (2). The pieces of prepared parchment glue can be ground as needed and dissolved in warm water at the desired concentration.
Parchment glue was made by cutting pieces of parchment into pieces and boiling them. A gelatin is then formed that produces a very pale, almost transparent glue with some flexibility.
It is not difficult to make your own parchment glue; you can use the remaining pieces of your parchment for this purpose. It is also possible to order from a parchment maker pieces of “cutting waste” that are quite suitable for this purpose. I have also made parchment glue myself, and as part of the recipe collection on the website, I thought it would be a good addition to explain how you can make this glue yourself.
(1) Daniel V. Thompson: The Materials And Techniques Of Medieval Painting. Page: 58-61
(2) Isinglass is an adhesive made from the swim bladder of sturgeon and is of high quality.
Recipe
100 grams of parchment pieces gives 50 grams of parchment glue.
- Make small pieces from bits of leftover parchment.
2. Take a piece of cotton and put the small pieces of parchment in it and tie it with a string.
3. Soak the bag with the parchment pieces in water overnight.
4. In a saucepan, bring 1 liter of water to a boil. Lower the temperature slightly so that the water stays just at a boil.
5. Now leave the parchment in the water gently, just at the boil, for 6 hours. If too much water evaporates add some water and stir lightly from time to time.
6. Squeeze out the ball of parchment in a strainer over a bowl.
7. Open the bag and pour the glue over a glass plate or oven dish. Make sure those are thoroughly clean!
8. When a gel forms you can make small cuts in the not yet completely dry substance. After drying you can then break off manageable pieces. Complete drying does take several days, you can then easily take the pieces off the glass plate and store them in a jar.
Sources:
Theophilus Presbyter (c. 1070–1125): De diversis artibus or Schedula diversarum artium (in three volumes, ca. 1125).
De Arte Illuminandi Anonymous, 14th century.
Cennino Cennini: The Artist’s Handbook, Il Libro dell’Arte.