Are you looking to dip your toes into the material work of traditional water gilding? Do you want to get to know the world of gesso gilding? How do you create traditional gesso paste? Is it really as easy as it looks?
All this and more today, as we explore the various ins and outs of gesso gilding and creating your own gesso paste.
Selecting the Glue
For real gesso gilding, whiting powder is mixed with animal hide glue and water, a real testament to just how old this process is. Nowadays, when water gilding there are two main options to choose from when looking to create a gesso mixture:
Hide Glue
This is produced from various animal skins which are pulverized together. It is light in color with high cohesion and no odor (despite the contents). It is highly refined, processed, and usually already formed into small cubes that can easily be applied. Hide glue has a bloom strength of 240 and is, thus, the most highly recommended choice for a gesso recipe.
Rabbit Skin Glue
This kind of glue is mainly produced from the shaved skin parts of rabbits (yummy). The cohesion is extremely high and, unlike the hide glue, there is a very distinctive color and odor. It is highly refined, consistent, already processed, and, again, usually formed into small cubes.
This glue has a bloom strength of 400, rendering it much stronger than hide glue. It is, thus, recommended for use with gilder’s clay in the manufacture of gilder’s clay bole rather than in prepared gesso with gold leaf on a gilded surface.
A Word on Bloom Strength
Choosing your glue for traditional water gilding might seem a little overwhelming especially if you are not quite accustomed to the process yet. However, you can easily compare their relative qualities by comparing their gel strength as defined by the bloom gelometer. This is essentially just a fancy way of measuring the rigidity of the gilding adhesive.
More specifically, the bloom unit is a measure of the force required to create a 4mm depression on the surface of a sample prepared using a specific formula. Thus, the higher the bloom, the more rigid and strong the glue, and vice versa.
Creating the Gesso
Once you have chosen your blue, you are ready to create the gesso.
Heat the glue until it is as hot as possible without boiling it. Gradually add it into a pot containing the whiting chalk. The amount will depend on the project you are working on. A good rule of thumb is to start with one cup of whiting.
Slowly add the hot glue slowly stirred in and mix thoroughly to produce a paste. The hot gesso should be the same viscosity as average light cream with further smoothness achieved by straining the mixture through cheesecloth, breaking up any clumps of whiting, and removing coarse material.
Testing the Gesso
You can now make a quick test of the gesso for air bubbles by brushing it onto a piece of wood or agate stone. Once you have allowed it to dry completely (and a hairdryer can help with this), then use 320 grit sandpaper to lightly sand the surface.
If the sandpaper removes the gesso too easily, then it is too thin. If, though, the gesso is hard and obvious scratch marks are left from the sandpaper, then the gesso is too hard overall. Return to the cooker and add more glue or whiting as needed.
Adding Pigment
Once you have your gesso all prepared and ready to go, you can add dry pigment to the mixture so as to achieve a variety of different color options. Ideally, you would use fine ground dry pigments, adding them to the whiting before the hot glue mixture is slowly stirred in.
Recipes for gesso can vary considerably, so experimentation is advised, especially if you intend to add dry pigment. The hardness of the gesso mixture can vary even more when adding dry pigment, so do an experiment at your own behest.
Storing the Gesso
Gesso actually has a rather limited shelf life and will begin to accrue mold over time. By storing unused gesso and/or glue in a glass container in a dark and cool environment, you can ensure that it lasts a little longer.
When you are ready and willing to use it again, return to the cooker and get out the mixture, reheating it as above. If there is mold or a smell that seems to indicate the presence of mold, discard it and create a new batch.
Final Words
So, there you have it! Hopefully, you are now well on your way to creating your own gesso paste and toward your goal of learning traditional water gilding.
FAQs Gesso Gilding
Gesso is the foundation of all traditional water gilding. Pronounced ‘jesso’, gesso is used to provide a thick and relatively hard coating onto the surface that is to be water-gilded. Its chief function is to fill in the small, barely perceptible (but still wholly important) grains in the wood. Once it has dried, it can be sanded down to the level of smoothness or coarseness that is desired by each individual circumstance.
Indeed you can. In fact, gesso is one of the foundational elements in the application of gold leaf, at least as far as traditional water gilding methods are concerned. Gesso’s chief function is to fill in the minute and barely perceptible holes and gaps that make up the grain of something. This is especially the case for wood which inherently is filled with such punctures. Once it has dried, you can then proceed to apply the gold leaf to the smooth surface, safe in the knowledge that there will be no interruptions to the gilding process, at least from the grain of the item.
The materials and steps by which you make gesso for water gilding are fundamentally rather simple, though can take a while to get right. Since recipes for the concoction of gesso can vary so wildly, experimentation with materials and their quantities is encouraged. The two principal materials are the glue itself and the whiting. The former was traditionally made from animal hide or rabbit skin and is typically still done with to this day – this is a traditional method of gilding after all. The latter is essentially just chalk.