THE METHOD AND SYSTEM FOR DRAWING ON SHEEP PARCHMENT AND ON PAPER,1 AND SHADING WITH WASHES. CHAPTER X
[…] And you may likewise work and shade with colors and with clothlets 2 such as the illuminators use; the colors tempered with gum, or with clear white of egg well beaten and liquefied.The craftsman’s handbook by Cennini, Cennino, active 15th century; translated by Thompson, Daniel Varney, 1902- ed
How to make a white gouache (biacca)
Water colors and gouaches were prepared to work on parchment and paper. The main binders were white of egg, also called glair, and/or gum arabic. Segreti per colori [Secrets of colours], an early 15th century treaties on colors and illumination, gives tens of color recipes of colors and binding media that best fit them, sometimes suggesting different binders for different uses of the same color. Below are a few examples:
65. How to grind azure to use with the pen and in body colour. […] And if you wish to use it with the pen or for miniatures, take the azure and distemper it with glue made from parchment clippings [gelatin/rabbit glue], or with gum water and prepared white of egg, and it will do well.
105. To make a splendid yellow, finer than orpiment or German giallolino […] Distemper it with clear ley [water mixed with ashes used for washing], and an equal quantity of prepared white of egg, and with powder of gum arabic, and let it remain together for two nights.
226. To prepare white lead for painting —Take the white lead, and wash it several times in hot water, and then take two grains of clear gum-arabic and 3 grains of white incense, grind them very well with a little clear water, and then add the washed white lead, and grind the whole together, and collect it and add to it as much gum-water as you think it will bear, and if it is too hard put a little fresh water to it, and it will do well.Secrets of Colors (Bolognese Manuscript), first half of 15th century, Mary P. Merrifield, Medieval and Renaissance treatises on the arts of painting : original texts with English translations
To make a white gouache for drawing highlights (called biacca in Italian), Cennino Cennini suggests using lead white mixed with two different binders. First he advises to use gum arabic to work with a dry brush in body color; and in the next chapter he suggests the usage of egg yolk to work with liquid medium (washes):
HOW YOU SHOULD DRAW AND SHADE WITH WASHES ON TINTED PAPER, AND THEN PUT LIGHTS ON WITH WHITE LEAD. CHAPTER XXXI
[…] When you have got this done, take a little white lead well worked up with gum arabic. (I will explain this to you later on, how this gum is to be dissolved and melted; and I will explain about all the temperas.) Ever so little white lead is enough. Have some clear water in a little dish, and moisten this same brush of yours in it; and rub it over this ground white lead in the little dish, especially if this is dried up. Then dress it on the back of your hand or your thumb, shaping and squeezing out this brush, and getting it empty, practically draining it. And begin rubbing the brush flat over and into the areas where the high light and relief are to come; and proceed to go over them many times with your brush, and handle it judiciously.
Then, for the accents of the reliefs, in the greatest prominence, take a pointed brush, and touch in with white lead with the tip of this brush, and crisp up the tops of these high lights. […]
HOW YOU MAY PUT ON LIGHTS WITH WASHES OF WHITE LEAD JUST AS YOU SHADE WITH WASHES OF INK. CHAPTER XXXIIThe craftsman’s handbook by Cennini, Cennino, active 15th century; translated by Thompson, Daniel Varney, 1902- ed
I advise you, furthermore, when you get to be more experienced, to try to put on lights perfectly with a wash, just as you do the wash of ink. Take white lead ground with water, and temper it with yolk of egg; and it blends like an ink wash, but it is harder for you to handle, and more experience is needed. […]
As you can see, Renaissance artists were very aware of various properties of colors and binding media they were using and knew when one binder or pigment would work better then the other. This is one of the reasons why it is very difficult to simulate the depth of color, variations of tone and texture we can see in some Renaissance painting masterpieces with colors “out of the tube” which components remain unknown as they represent a trade secret.
Let’s do some Alchemy!
White gouache ingredients:
Gum Arabic is a hardened sap of acacia tree. It can be powdered and dissolved in water [N.B. saps that can only be solved with help of solvents are called resins] to make a solution with adhesive ability that can be used in many ways.
Gum arabic was very widely used in past to make color binders, dyes and gilding boles. Today it is still used for drawing, painting, photography, printmaking and even in food industry.
Since the very early days of our civilization eggs are used in a variety of fields. In art, each part of the egg has its particular uses:
- Egg yolk is mainly used as binder to work on panels and to make emulsions
- Egg white (also know as glair) is used as binder to paint on parchment and paper, it creates a very hard and shiny veil and thus sometimes white of the egg was used as varnish
- Egg shells, rich with calcium, were also powdered and used as an additive to colors or even as pure pigment.
White lead (lead carbonate), artificially produced since the times of ancient Greeks and probably even earlier, or its mineral near equivalent cerussite were until quite recently very commonly used in painting of any kind and medium, all branches of industry and even cosmetics.
Unfortunately, the toxicity of this pigment has led to severe trade and production restrictions and this pigment is now largely replaced by zinc an titanium whites.
Clean water, typically rain or spring water was used. We will use distilled water.
- Honey or glycerin: to make the color denser, improve viscosity and make it more elastic, honey or glycerin is sometimes added.
- Preservative: vinegar, wine, cloves essential oil, or today you could also use a chemically produced biocide such as Nipagina (Methylparaben) or Phenol. If you do not intend to store the color preservative is not necessary.
- Chalk: calcium carbonate is often added to pigments as a filler when creating opaque gouache colors.
Modern, based on historical recipes
A very basic recipe could be as simple as mixing whipped egg white with powdered pigment, but we can improve its qualities and shelf (or, actually, fridge) life by adding gum arabic and wine.
- Titanium white
- Gum arabic
- Distilled water
- White wine or vinegar
Step 1: Prepare the egg white
Beat egg white into a froth and set it aside for 1/2 hours. Then separate the foam and the liquid deposited at the bottom by pouring the liquid gently to a different container.
Step 2: Prepare a 30% Gum solution
Powdered gum arabic can be easily dissolved in water quite easily, to speed up the process you can warm it up with a water bath (Bagno Maria)
Step 3: Make the medium:
- 1/3 Gum solution
- 1/3 Egg white
- 1/3 White wine (or if you use vinegar use 1/6 vinegar and 1/6 water)
Step 4: ADD the pigment:
If you want to store the color in paint pans, like watercolors, you can add honey or glycerin and grind the pigments directly with the binder to get a more viscous and dense paste.
Otherwise, prior to be mixed with any water-soluble binder, you should grind the pigment in distilled water (the amount of water will change depending on the pigment properties). This way you can store the pigment ground in water for as long as you want and use it (temper it) with any water based medium you like (gum, egg yolk or white, casein, glue and acrylic) or even use it for fresco painting.
An alternative way of preparing the egg white:
XXXI.  Of the manner of preparing white of egg for tempering colours.Manuscripts of Jean Le Bègue, 1368–1457, Mary P. Merrifield, Medieval and Renaissance treatises on the arts of painting : original texts with English translations
— When you are going to prepare white of egg, take a filter, and dip it in water, and wet it well, and afterwards receive the white of egg mixed with water in this filter, which must be folded up so as to be pointed at the bottom and open at the top; and so, squeezing it, make it pass through seven or eight times, or oftener or less frequently, if necessary, for you must do this until the white of egg becomes like water, and runs through without drawing into threads. Then take it and put it by; or, if you wish, write with it. Two vases are necessary for preparing it.