During the Renaissance period, which spanned from the 14th to the 17th century, the use of glues was widespread and played an important role in various artistic and craft activities. The most common types of glues used during this time were made from natural substances such as flour, cheese, animal hide, bones, and fish. These glues were commonly used in the production of paintings, sculptures, bookbinding, and woodworking.
The quality of the glue was crucial to the durability and longevity of the artworks, as well as their appearance. Therefore, artisans and craftsmen paid close attention to the preparation and application of these glues.
Flour-paste glue for paper
Materials & Tools
Flour-paste, flour-glue or wheatpaste are all names of a simple glue used probably from the day humans have started making flower and still commonly applied by artist, artisans and restorers that work with paper.
The role of gluing agent in this case is played by gluten proteins. The glue is reversible and doesn’t damage the bound material and thus it is the material of choice of many paper and book conservators.
HOW YOU MAKE BATTER OR FLOUR PASTE. CHAPTER CV
The craftsman’s handbook by Cennini, Cennino, active 15th century; translated by Thompson, Daniel Varney, 1902- ed
[…] There is one size which is made of cooked batter, and it is good for paper workers and masters who make books; and it is good for pasting paper together, and also for fastening tin to paper. We sometimes need it for pasting up papers to make stencils. This size is made as follows. Take a pipkin almost full of clear water; get it quite hot. When it is about to boil, take some well-sifted flour; put it into the pipkin little by little, stirring constantly with a stick or a spoon. Let it boil, and do not get it too thick. Take it out; put it into a porringer. If you want to keep it from going bad, put in some salt; and so use it when you need it.
Common uses of this paste include: gluing pieces of paper, making collages, chine collé technique in printmaking, laying paper on canvas or panel, papier-mâché, priming canvases and more. Vasari gives and interesting example of usage of this paste: stretching cartoons on the wall:
§ 77. Sketches, Drawings, and Cartoons of different kinds.
The cartoons are made thus: sheets of paper, I mean square sheets, are fastened together with paste made of flour and water cooked on the fire. They are attached to the wall by this paste, which is spread two fingers’ breadth all round on the side next the wall, and are damped all over by sprinkling cold water on them. In this moist state they are stretched so that the creases are smoothed out in the drying.
Giorgio Vasari (1511-1574), Vasari on technique; being the introduction to the three arts of design, architecture, sculpture and painting, prefixed to the Lives of the most excellent painters, sculptors, and architects
Making the Wheat Flour Paste
Medieval and renaissance recipes of the paste are not very precise, probably because this glue was used in every household and there was no need to go in details:
33. Cement for joining parchment is thus made
Manuscripts of Jean Le Bègue, 1368–1457, Mary P. Merrifield, Medieval and Renaissance treatises on the arts of painting : original texts with English translations
[…] But if you wish to join paper only and not parchment, wheat-flour or powdered bread-crumbs mixed with pure water and slightly boiled is very good for paper. But if you mix a little gum-arabic or whipped white of egg with it, it will do for parchment.
Chapter 52. Applying the Solder to Gold
Theophili, qui et Rugerus, presbyteri et monachi, libri III. De Diversis Artibus: seu, Diversarum artium schedulaWolfenbüttel, archive.org | Herzog-August Bibliothek cod. Guelph Gudianus, lat. 2°69, fol. 86r: incipit
[…] You should also have some fine flour of wheat or winter wheat, which you should mix with water in a small vessel and put on the fire to heat a little. Into this dip lightly the underside of each of the settings and so fix them firmly in place. […]
A cartoon for the fresco of the same name in Vatican is assembled from about 210 sheets used by Raphael that were glued to a support with flour paste.
The main steps to prepare the glue:
Ingredients:
- Distilled water (500ml)
- Flour (100gr)
- Additives (optional, see the list of additional ingredients)
Step 1: heat the water
It should almost boil
Step 2: Mix flour and warm water.
Proportions are nearly 1 to 5, but this was usually done by eye, depending on the desired density of the paste. You can sift the flour directly into the pot, or add sifted flour little by little.
Step 3: Condense it a little more
Continue heating gently and stirring until it gets quite dense.
Step 4: Add the additives if necessary
If you want to store it, add a preservative, if you want to change viscosity or adhesive properties you can add glycerin, gum, alum or whipped egg white (the last one would be better to add when the paste is already cold).
Additional ingredients:
- Preservative: Cennini suggest to use salt, but you can also try vinegar, wine or today you could use a chemically produced biocide such as Nipagina (Methylparaben), phenol or formaldehyde. If you do not intend to store the glue it is not necessary.
- Alum (Aluminum Ammonium Sulfate and Aluminum Potassium Sulfate), number of modern sources recommend adding alum as a hardener (around 1 teaspoon for 500ml of water will do).
To learn more about glues and adhesives used during the Renaissance and Middle ages, check out A Practical Guide to Medieval Adhesives by Maya Heath
Animal Skin Glue
Materials & Tools
Hide glue, also known as animal glue or rabbit skin glue, is a type of adhesive made from animal collagen, usually from the hides of rabbits, cattle or horses. It has been used for centuries in painting, woodworking, musical instrument making, and bookbinding. Here are some key points about hide glue:
- Preparation: Hide glue is sold as a dry powder or in granular form. It is mixed with water to create a liquid glue that can be applied to surfaces.
- Application: Hide glue is applied while it is warm and liquid, usually with a brush. It sets quickly as it cools, so it is important to work efficiently. Some people prefer to keep the glue warm while working by using a glue pot or other heating device.
- Strength: Hide glue creates a very strong bond, but it is not waterproof. It is also susceptible to damage from high humidity or extreme temperatures. However, it can be easily repaired by reheating the glue and reapplying it. It is important to follow the instructions for mixing the glue, as too much or too little water can affect its strength.
- Shelf life: Dry powder or granular hide glue can be stored for extended periods if kept in a cool and dry place. However, once the hide glue is mixed with water, its shelf life is relatively short, and it can begin to spoil or become less effective after just a few days. To increase the shelf life of mixed hide glue, it’s recommended to prepare a strong glue mixture with a concentration of 20% or more and store it in the refrigerator. Additionally, preservatives can be added to the glue to extend its shelf life and prevent the growth of mold.
- Clean-up: Any spills or excess glue can be cleaned up with warm water while the glue is still wet. Once it has dried, it can be scraped or sanded away. It is important to keep tools and surfaces clean while working with hide glue, as it can be difficult to remove once it has dried.
Preparing the Hide Glue
CHAPTER XVI. HOW THE GREEN TINT IS MADE ON PAPER FOR DRAWING; AND THE WAY TO TEMPER IT.
Then temper the aforementioned substances with size of the following quality and strength: Get a leaf of druggists’ glue (not fish glue) and soak it in a pipkin for six hours in enough clear, clean water to fill two common goblets. After soaking, put the pipkin on the fire to temper it, and skim it when it boils. Once it has boiled and the glue is fully dissolved, strain it twice.
The craftsman’s handbook by Cennini, Cennino, active 15th century; translated by Thompson, Daniel Varney, 1902- ed
Recipe:
Preparing rabbit skin glue with a double boiler is a common method used by artists and craftsmen. Here are the steps involved:
Ingredients:
- 1 part glue (by volume)
- 4 parts distilled water (by volume)
Concentration (Strength):
To create different concentrations of glue, you can start with a 20% concentration and dilute it accordingly. For example, you can achieve a 10% concentration by diluting the 20% concentration by half, and a 5% concentration by diluting it by half again. If you need a 15% concentration, you can mix equal parts of the 20% and 10% concentrations etc. This allows for greater flexibility in creating the desired consistency for your specific project.
Preparation:
- Soak the rabbit skin glue in cold water overnight or at least for several hours until it softens.
- Transfer the glue and the water to a double boiler. If you don’t have a double boiler, you can use two pots or a heatproof bowl placed over a pot of simmering water.
- Gently heat the water in the bottom pot of the double boiler until it reaches a temperature between 120-140°F (49-60°C).
- Stir the glue mixture until it dissolves completely and becomes smooth.
- Once the glue is fully dissolved, remove it from the heat source. Never allow the glue to boil – overheating will compromise its adhesive properties.
- Use the glue while it is still warm and fluid, as it will start to gel and solidify as it cools.
It’s worth noting that some artists may add additional ingredients, such as vinegar or glycerin, to modify the properties of the rabbit skin glue. The exact ratios and ingredients used can vary depending on the artist’s preferences and intended use of the glue.
Additional ingredients:
- Salt: Adding a small amount of salt to hide glue can help to extend its shelf life by inhibiting the growth of microorganisms that can cause spoilage
- Glycerin: Adding glycerin to hide glue can improve its flexibility and reduce its brittleness, making it more durable and less likely to crack over time.
- Acetic acid: Adding acetic acid to hide glue can increase its water resistance and help to prevent the glue from becoming brittle over time. However, this should be done with caution, as too much acid can weaken the glue and cause it to fail.
- Preservative: Cennini suggest to use salt, but you can also try vinegar as a natural preservative. Nowadays, commonly used preservatives for hide glue include: phenol, formaldehyde, and sodium benzoate. Nipagina (Methylparaben) is also commonly used by Italian restorers. If you do not intend to store the glue, preservative is not necessary.
- Alum (Aluminum Ammonium Sulfate and Aluminum Potassium Sulfate), number of modern sources recommend adding alum (around 1 teaspoon for 500ml of water will do) that can improve tack and adhesion, making the glue more effective for difficult-to-glue surfaces.
Overall, hide glue is a versatile and reliable adhesive that has been used for centuries in various crafts and trades. It requires some care and attention during preparation and application, but it can create very strong bonds that are easily repairable.