Gilding on polyment with gold foil is one of the most ancient and widespread methods for interiour objects (icons, frames, etc). 

One of the earliest written evidences of the use of gold leaf in painting is contained in the Lucca manuscript of the VIII century. In the XIII and XIV chapters of this collection of recipes, it is described in detail about the preparation of the so-called asisa honey from "thin" plaster and Armenian bolus with the addition of a small amount of so-called asisa honey (2 primers for parchment and the application of gold leaves on it.  The compiler of the collection considered it necessary to point out (Chapter XIV) that in this case one should act as "artists do when they gild their pictures painted on wooden supports." No less important is the indication of the ornamentation of the gilding: after the gold is polished, "it is possible to draw lines on it and puncture" it.

Such instructions can be found in manyother later treatises and manuscripts. The most detailed collection of them is contained in the treatise of Cennino Cennini. First of all, Cennini devotes several chapters to the process of gilding with gold leaf on a rigid base, a gilded primer composed of Armenian bolus rubbed with whipped egg whites diluted with water; this composition was applied with a brush to the primer up to three or four times with short intervals (Ch. 131,  132). However, Cennini also knows another method, when "following the example of the ancients" gold is laid without a gypsum primer directly on the canvas, previously covered with green earth, worn "on either of the two temperas" (Chapter 133). 

The polyment,  on which the gold leaf is applied, is a complex paste. The third book of the treatise of Heraclius reports on the different compositions of the poilyment for gilding: in one case, it is ocher mixed with parchment glue and churned egg white, and in the other, gypsum, white chalk and cinnabar.The main component of polyment is a special clay. There are deposits of such clay in Italy, France, Germany, the USA, and Canada. But the best clay, which has an amazing red color and differs from other varieties in finer grinding and greater hardness, is mined in Armenia. The composition of the polyment varies according to the available materials, in Russia,i.e. it is: clay, sturgeon or rabbit glue, a drop of linseed oil. 

Application: dry clay in pieces is soaked in an emulsion consisting of egg white mixed with water, then rubbed on a marble board until the mass becomes thick. The pounded mass is placed in a vessel; the rest of the emulsion is poured into it and mixed thoroughly. Before gilding, the resulting mass must be melted in water bath and applied with a brush of squirrel or marten hair to a surface ideally prepared for gilding in an even layer, let it dry, and then polish with a horsehair cloth. 

After that, the sheet of gold is carefully moved with a brush from the book of gold leaves to the gilder's pillow. Here it is cut with a gilder's knife to the desired size and shape. Then the polyment is covered with alcohol (rakia or vodka) and a pre-cut sheet of gold is drowned in it. The sheets should lie without wrinkles, one on top of the other with an overlap of a few millimeters. Vodka slightly dissolves the glue included in the polyment, draws in the leaf, and then evaporates. A sheet of gold becomes one with the polyment, and irregularities can no longer be corrected. After applying the gold (after 12-24 hours), it can be polished. To obtain a soft shine, gold is polished with a soft cotton swab, nylon stocking or squirrel brush. A bright shine can be achieved by polishing with an agate (tooth) stone. Previously, gold was polished with a bear or boar tusk, so the classic shape of the tooth (an agate tool) resembles a boar's tusk.

In the image supra are visible traces of burnishing left on the gilded surface, revealed through the opportune direction and angle of lighting (20x). This finding for itself solves the questions concerning the composition of the polyment, as only such based on glue and minimal percenbtage of wax or oil can be polished. Well visible underneath the gold foil also the preliminary designs in brush, in red over oche,r which is the main component of the polyment, therefore the use of Armenian bolus is to exclude here.