The use of gold leaf for backgrounds, halos and decoration in icons is not simply for aesthetic reasons. Although burnished polished stamped and tooled icons can be very beautiful, the use of gold leaf in icons is primarily for a specific theological purpose. Gold in the Byzantine language of colour signifies light. Not simply daylight, but the light of God, more specifically, the gold in icons is spoken of as being like the uncreated light of God as witnessed by the Apostles on Mt Tabor when they were present at Christ’s Transfiguration.
The use of gold leaf in art has a very ancient history, it can be seen on painted Egyptian Sarcophagi and many Greek and Roman statues of the deities of the Classical Pantheon were painted and gilded. The classical craft of applying and polishing gold on a prepared wooden support or surface became part of the language of the icon from their earliest incarnations. The very oldest icons of Christ and St Peter which have survived At St Catherine’s Monastery in Egypt are both gilded.
Today iconographers use a variety of techniques for gilding. The technique regarded as both the most rewarding and the most challenging, is ‘Water Gilding’, this technique is probably Egyptian or Greek in origin and was used by the iconographers of Byzantium and the Byzantine Empire. It is certainly the technique used by the Early Italian masters such as Duccio, who was himself the pupil of a Greek master iconographer. Perhaps the earliest and certainly the most comprehensive written description of the technique can be found in ‘Il Libro dell Arte’, The Craftsman’s Handbook, a fifteenth century painters manual written by Cennino d’Andrea Cennini, pupil of Taddeo Gaddi, a follower of Giotto.
Water gilding is normally the technique employed on a panel painting or icon; it works best on a surface that has been specially prepared with gesso, a white plaster made from chalk, marble dust and animal glue such as rabbit skin or gelatine.
The brilliant white gesso is rubbed, scraped or sanded to achieve a perfect flawless surface on which to gild. Any flaws scratches or marks will show through the polished gold. Decorations and halo lines can be incised into the gesso at this point.
Next many layers of red clay like pigment called ‘bole’, mixed again with animal glue is applied dilute and warm to the areas to be gilded.
This is in turn polished to a high gloss finish and the panel is now ready to gild.
Special tools are required for handling and applying the gold leaf. The gold used is almost pure, traditionally 23, 1/2 carats, pure gold is unsuitable, as it fragments and breaks too easily in use.
The gold comes in small books, bound between layers of tissue paper. From the book it is laid onto a special suede covered mat called a ‘gilders cushion’, then cut with a ‘gilders knife’, a long carbon steel, flexible knife into the shape required. Most gilders work with half leaves, applying and slightly overlapping the gold half a leaf at a time. To pick up and lay down the gold the gilder uses a special squirrel hair brush, a ‘gilders tip’, which is traditionally exactly the size of half a leaf of gold.
When the gold is cut ready, the gilder brushes the tip against his skin to pick up a little surface moisture/body oil; the gold is so fine that it will stick to the slightest hint of moisture on the surface of the tip. When the gold has been picked up ready to use, the gilder wets the clay surface with water with a tiny amount of animal glue and some alcohol in it with a large squirrel brush, the ‘gilders mop’. The gold on the tip is then laid on the wetted area, as the water soaks into the clay and evaporates the gold leaf is pulled down onto the clay and sticks hard. About an hour after it has been laid the gold can be polished, or burnished with another special tool made from a piece of cut shaped and polished agate or hematite.
Once the gold has been polished to a mirror like reflective shine and left for a day or two to set properly it can be embellished with stamping or tooling. A variety of tools can be used for this, ranging from specially made metal punches with patterns such as flowers, crosses, or stars cut into them, to simple ball punches of various sizes that can be used singly, or in clusters to make simple designs and patterns. The small ‘stippling’ marks are made with tiny ball punches used repeatedly simply with hand pressure, the bigger punches are tapped carefully with a wooden or rubber mallet.