In 1904, Franz Birbaum gave a talk to the workmasters and designers of Saint Petersburg.

Therefore, we have in our possession a first-hand lecture by the greatest Fabergé specialist directed towards the Russian Society of Industrial Arts. Birbaum was one of the founders of that professional association, whose purposes was to advance knowledge of the various aspects of industrial art production within the field. This is one of the very few primary source documents into the methods of manufacture and production of the house of Fabergé

We are grateful to Tatiana Fabergé and Valentin Skurlov for permission to republish this article from their work: Fabergé: A Comprehensive Reference Book, 2012. pp. 363-369.

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The richness of colours that we have inherited from Byzantium and the Far East has always been an inseparable companion of our national folk art and one of the components of its quality. In view of the value of this rich folk art, we should pay particular attention to the best possible methods of expressing it, and I shall not hesitate to assigning first place to enamel. No painting can compete with the strength and richness of shades of enamel or with its solidity and durability. It is not affected by the action of time and acids and retains all the colours conferred on it by the artist for hundreds of years.

It is therefore sad that a subsidiary using enamel should be regarded as a negligible quantity, for where enamel production is concerned we have no research and practically no leading examples. Even our art institutes have not opened any classes specialized in this topic. The result of this state of affairs is that enamel, an element of such great value in our folk arts, has been neglected and is now used only in stereotypes, i.e. not very artistic objects made by artisans.

We are thus faced with a twofold task, first, that of training producing craftsmen and imbuing them with artistic feelings, and secondly, teaching them the manufacturing methods, so as to enable them to use enamel knowingly as an interpreter of their composition. In order to develop the first-named task, I shall begin by describing the techniques, while reducing the historical aspects to a minimum. This description will of course provide only the concept of production, but I hope that with your indulgence and support I shall succeed in creating practical enamel workshops intended for members of our society who would like to learn more about this subject.

Enamel is nothing but a mass of transparent matter, or glass. Various metal oxides added to this mass give it different colours and, where necessary, lend it opacity. Enamels belong to one of two main families, that is to say, they can be transparent or opaque (non-transparent). For the processes of their use on metal, they can be divided into the following five categories:

· Cloisonné

· Champlevé(on a hollowed-out surface)

· Plique-à-jour(perforated stained glass)

· Bas-relief

· Paintedon iron and other metals.

The difference between cloisonné and champlevé enamel lies in the fact that in the first case use is made of partitions of short rows of soft metal (gold or silver) fixed to the smooth surface or the sides of the article by means of soldering. In the second case, the surfaces to be filled with enamel are hollowed into the plaquette itself or into the object by means of instruments.

Perforated enamel (plique-à-jour) differs from the first two types in that there is no metal base and the enamel plays the part of stained glass. When it is in bas-relief metal ornaments or very low relief figures appear under the enamel. The difference lies in the layers of enamel, which make some parts of the bas-relief deeper than others, making them stand out.

Although painted enamel looks like ordinary painting, it must be divided into two kinds:

1. Painted enamel, in which practically every effect is achieved by the position of the Various layers of enamel.

2. The method of painting on porcelain.

Now that we have enumerated these different methods, we can subject them to a brief historical review.

In ancient times, enamel was already known by the Egyptians, Persians and Etruscans. It may be assumed that the Egyptians discovered enamel through the Phoenicians.

Unlike the technique applied later, the Egyptians used enamel in the same way as mosaic – that is to say, they cut out small pieces of a given shape, dimensioned them and fixed them in already prepared partitions. Enamel thus played a part similar to that of precious stones. It was often to be found in wings symbolizing falcons and scarabs. The best examples of Egyptian enamels are to be found in the Louvre Museum. There can be no doubt that enamel was known to the Etruscans, and traces of it may be found on the decorative objects, weapons and utensils of ancient Gaul. In addition, we have the written descriptions of Philostrates, who stated that «The Barbarians of the Ocean shores know how to cover metals with colours subsequently become hard as stone».

As from the sixth century A.D., enamel may be found in Byzantine gold objects, using the cloisonné method exclusively. The best-preserved examples of this enamel appear in Russia, in the Zvenigorod and Botkin collections, and largely consist of representations of Jesus Christ, the Virgin Mary, the Evangelists and various Saints. The technique used in these works is so advanced that it astonishes the best of contemporary enamellers. These enamels are used on very fine plaquettes of pure gold with partitions of the same metal. Owing to the extreme fineness of the plaquettes - that of an average piece of paper - the place occupied by the figures was hollowed, partitions were set up in the contours thus obtained and the hollows were filled with enamel.

From Byzantium cloisonné enamel spread westward to France, Germany and Italy, where it was used from the 9th to the 12th century A.D. Owing to its high cost, it was used only in small gold objects. When transported to Russia, these differed from cloisonné articles by the fact that they took the form of fine threads; these filigrees were mainly used on silver and are also distinguished by the fact that the enamel remained under the filigrees, which were not polished at the end of the operation.

During that period the number of churches increased greatly in the West and the demand for liturgical objects necessitated seeking cheaper materials. The cloisonné process, suitable for gold and silver, became very difficult to use on copper, owing to the hardness of that metal: the partitions were difficult to solder and to fashion into curves; for this reason, champlevé enamel came to replace cloisonné and transparent enamel to lose its preponderance over the opaque. The largest producer of champlevé enamels worked in the town of Limoges in France.

The champlevé enameling process yields a wide variety of results, according to the way in which the design is enameled – leaving the metal on the background or, on the contrary, leaving the metal for the figures so that the enamel covers the background. The advantage of this process over cloisonnélies in having a contour which can be enlarged or reduced according to the design, thus making the method more expressive.

Towards the end of the 13th century, enamels in reliefappeared at Pisa and Siena in Italy and in Montpellier in France. Although the output was enormous and continued until the 19th century, very few examples of this enamel have survived until modern times, because their execution on gold or silver often caused them to be destroyed for the value of those metals. Their emergence was extremely harmful to Limoges enamelery, by completely blocking the champlevéprocess, which remained out of use until the 15th century.

Enamel perforated on glass (plique-à-jour) appeared in Italy during the 14th century. A description of this technique may be found in the writings of Benvenuto Cellini: «ln a metal box shaped according to the mass of enamel to be obtained, a fine layer of earth is spread with a small brush, so as to prevent the enamel from sticking to the metal. The design, consisting of small strips of metal as for cloisonné, is lowered into the box. The appropriate amount of enamel is inserted, and after baking a mass oftransparent enamel is removed from the little box and is left to set,in the manner of precious stones».

A brilliant period of painted enamel began in Limoges with the 15th century. Most of these enamels were executed in a single shade of colour and are known as grisaille and camayeu.The predominant colours were violet and blue, with a black background; objects of all these colours are often to be found. In these articles, white enamel was covered with others, transparent or of different colours. Limoges enamels, in the form of small plaquettes with representations of saints, some of considerable size, were used to decorate altars and other objects of worship. With subjects drawn from mythology and the Old Testament, they were used as panels for furniture, small boxes and so forth. The same process was used to cover dishes, vases and various valuable utensils. The magnificent enamels of Limoges degenerated into painting on enamel which was intended to be closer to ordinary painting. Those who adopted this method devoted themselves almost entirely to miniatures, portraits and other subjects usually decorating the covers of small boxes and snuffboxes. This genre prevailed almost until the end of the 19th century, when the renaissance that took place in all artistic production also affected enamel. The enamelers of our day, better equipped with chemical knowledge, have not only breathed life into past processes, but have brought them to a degree of perfection hardly imaginable by their predecessors.

Here again, France provided the I largest contingent oftalented I enamellers: the names of Grandhomme, Thesmar, Tourette, Hirtz, Lalique, Feuillatre and Houillon are world-famous. In England, Fischer is known for his painted enamels and in Switzerland Itten is renowned for his decorative work.

After this detailed description of the various uses of enamel, it is essential to refer to metals.

Not all metals are suitable for enameling, and preference must be given to those which are not susceptible to oxidation – gold, silver and platinum. Copper, iron etc. are less suitable. Accordingly, gold and silver of the highest grade must be used, that is to say, 72 to 88 units for gold and over 88 units for silver. The presence of copper has the effect of deteriorating the enamel and changing its colour, but this effect can usually be attenuated by covering the metal with a layer of enamel. Accordingly, it is preferable to use opaque enamel when working with copper or iron and, if transparent enamel is used, the metal should be covered with a layer of flux.

Metals intended for enameling should be subjected to cleaning. We shall go further into this matter when we study the various processes of using enamel.

ENAMEL

As we have already said, the main component of enamel is a colourless mass of glass known as flux. This is a casting of glass comprising lead oxide (minium), quartz and borax. It plays the same part in enameling as water does in watercolour painting. Flux may be refractory or non-refractory. Augmenting the quantity of minium and borax will give an easily melted enamel, while increasing the amount of quartz and reducing that of minium and borax will give a refractory enamel.

Two fluxes are generally used in the composition of enamel:

· Refractory

I. 12 parts borax baked on a sheet of metal; 12 parts quartz powder (silica); 6 parts minium.

• Easily melted

II. 12 parts quartz; 30 parts minium. There are also the following mixtures, especially intended for working on gold:

a) 3 parts silica; 2 parts minium; 2.5 parts potassium.

b) 3 parts silica; 5 parts minium; 1 part potassium.

c) 2 parts silica: 3 parts minium: 10 parts potassium.

d) 2 parts silica; 2 parts minium; 1 part heated potassium.

In each case the mixture is melted in a crucible, moistened with water, ground and dried. In order to give colour to the flux, various metal oxides are added to it. A larger amount of oxide intensifies the shade, while the colour becomes lighter with a smaller quantity of oxide. The composition of various enamels may be set out as follows:

• Yellow enamel

I. 10 parts flux; 1-2 parts silver chloride.

II. 4 parts flux; 1 part antimony oxide. Uranium oxide also gives a golden yellow colour.

• Green

I. 10 parts flux; up to 2 parts chromium oxide.

II. 30 parts flux; up to 2 parts black copper oxide. Iron oxide gives a bottle-green colour.

• Blue

10 parts flux; up to 2 parts cobalt acid. A mixture of cobalt oxide with copper gives a turquoise colour.

• Violet

30 parts flux; up to 2 parts manganese oxide

• Purple

12 parts flux; up to 2 parts purple. Copper oxide and chlorous gold oxide also give good results Purple is a solution of gold in aqua regiamixed with a solution of tin salt from which the purple powder separates after a lengthy period of sedimentation. Alcohol is added to accelerate the separation.

Brownand blackenamels are obtained by melting iron oxide with manganese and flux.

The base for opaque enamels is obtained as follows: 10 parts of pure lead and 20 parts of tin are heated and mixed together until the whole becomes dirty yellow; this oxide is turned into a powder which is washed to eliminate all traces of metal and is finally dried. To make an opaque flux, the minium must be replaced by this oxide and the necessary oxides added to the flux to give it the desired colour.

As the manufacture of enamel does not enter into our terms of reference, these data concerning its composition should suffice, particularly since all sorts and forms of enamels are available on the market.

It is very important to work with enamels having the same melting point and the same colour stability, as unstable enamel turns yellow and dull if heated repeatedly. Before using any kind of enamel in an operation, it is essential to carry out all possible tests in order to avoid failures, which are in most cases irreparable.

ENAMELLING OVENS

Fabergé workshop, circa 1903. Courtesy of the Fersman Museum

These ovens are made of refractory earthern bricks, and various fuels are used for firing in them – birch-tree charcoal, coke, gas or petrol. In ovens burning charcoal or coke, the muffles are left open, but with petrol or gas they are closed, in order to protect the object from direct flames.

Whatever fuel is used to heat the oven, it is ready for firing when the muffle Is Incandescent and turns bright red. The object to be fired must be dried until ail the water has completely evaporated and must then be placed on an iron sheet or on refractory earth and little by little but not immediately introduced in the muffle or in the oven. When baking without a muffle, care must be taken not to have too strong a flame.

At the point of baking the object, it is essential to concentrate all one's attention on avoiding melting it and subjecting all its surfaces to an equal temperature. When the enamel has melted, the object is taken out and allowed to cool gradually. The melting temperature of enamel on gold and silver is approximately 8oo°C.

PREPARATION OF THE ENAMEL

Enamel is sold in pieces and is turned into fine sand for utilization. To this end it is ground in a porcelain or agate mortar with a porcelain or agate pestle. Grinding must continue until transformation into a fine sand, but not into a powder, since that would harm its fusion. At this stage the sand is repeatedly washed in water to which a small quantity of nitric acid has been added. It is advisable to use distilled water for the last washing. Enamel prepared in this way is kept in small boxes with water.

PROCEDURES FOR APPLYING ENAMEL

CLOISONNÉ ENAMEL

The partitions consist of fine rows of pure gold or silver with which we create the contours of the design, using small pincers. When the components of the contours are ready, they are placed on the plaquette and soldered down.

In some cases soldering is undesirable because particles of filings may appear on the base prepared for the enamel, and the following process is then applied: the places on which the partitions are to be laid are covered with a thin layer of slightly warmed flux. This melts, and the partition is affixed to it while cooling. By the side of this partition, a small quantity of flux is placed to the first layer during the next firing in order to fix these partitions. When places have been prepared for the enamel in one way or another, enameling strictly speaking can begin. Each object to be enameled must be washed very carefully, and every trace of grease and of any foreign body must be eliminated. The procedure is as follows: the object or plaquette is heated, avoiding making it red hot, as that will reduce the brilliance of the metal and the freshness of the work – fatal to transparent enamel. After heating, the piece is cleaned, first in diluted nitric acid and then with soap on a small brush, and is dried after several rinsings in water. It is then ready to receive the enamel, on condition, however, that the places to be enameled are never touched by any hand.

The enamel powder diluted in water is spread by little scoops over specified places, but not in thick layers, so as to avoid the formation of blisters. After the spreading of each layer, excess moisture is extracted with blotting-paper carefully applied round the edges. The object is then dried by means of a spirit-lamp until the water has completely evaporated, and only then will the object be ready for firing. If the enamel is to be levelled and polished, the last layer must be applied in such a way that the enamel covers the edges after firing.

At this point mention should be made of a precaution that enamellers must bear in mind. Owing to differences in the dilation rates of various enamels and metals, plaquettes and objects run the risk of buckling, so that the enamel may fall out of the metal in small fragments. To avoid this, the reverse side of the plaquette is covered at the same time with flux or with the remainder of different enamels – a layer known as counter-enamel.

In addition to this, an iron template of the same shape as the plaquette and covered with powdered refractory red earth, must be kept ready for the firing period. While the plaquette is still soft, it is placed on the template by small scoops or a metal stick. The refractory earth prevents the counter-enamel from sticking to the template.

CHAMPLEVÉ ENAMEL

As we have already said, the manufacture of these enamels Is based on a sufficiently thick metal plaquette in which hollows are dug by means of instruments and are subsequently filled with enamel.

First of all, the design is transferred to the metal with a clear indication of the parts which must remain intact (to ensure that the pencil or ink is fixed, the metal should first be covered with a very fine layer of gum).

The design to be transferred is drawn by a stylet in a fine engraved line. The places to be filled with enamel are then dug out with a flat stylet.

For the last-named operation, it is essential to ensure that the sides of the hollowed areas are vertical, since the designs will otherwise be spoiled after polishing. It is obvious that the deeper the hollow, the darker the transparent enamel will become.

When working on copper and ferrous metals, it is necessary to dig deeper, especially where opaque enamel is concerned. Etched engraving is used to facilitate work on copper: the metal parts to be retained are covered with lacquer and the engraving is effected by nitric add, as in the case of etching. When the necessary depth is attained, the lacquer is removed, the object is washed and the design is corrected with a stylet where necessary. The hollows intended for the transparent enamel may eventually be ornamented with engraving or, for large areas, be worked with a rose-engine. After the metal has been cleaned, the enamel covering process can begin, in the same order as for cloisonnéwork.

In all kinds of enameling work, a method which can produce magnificent results in the hands of an artist is that of paillons.These sequins made of sheets of pure silver or gold are placed under transparent enamel in the places where one wishes to obtain a special brilliance or particular intensity of colour in the enamel. The sequinsare made as follows: a very accurate template is taken of the places where the sequinsare to be placed. A sheet of the chosen metal is then placed on a smooth pearwood board. It is covered with the template and a very sharp knife is used to cut out both the template and the sequin. When a large number of similar shapes and dimensions of the sequin are needed, a special punch is made to cut out the required shape by pressing on the metal sheet.

The sequin is fixed to the lower layer of enamel as follows: a small brush is used to cover the prepared place with a light, sticky flux or better still with the juice of crushed quince seeds. The sequin is picked up with small pincers, placed in the desired position and lightly pressed. To dry the glue definitively, it will suffice to bake it slightly.

When using this method, it must be borne in mind that the metal will change the colour of the enamel covering it: gold will accentuate the warmth of the colour, while silver or platinum will have the opposite effect. It may be accepted as a rule that transparent enamel will acquire different shades on different metals.

PERFORATED ENAMEL IN STAINED GLASS (PLIQUE-À-JOUR)

A pair of Russian silver-gilt plique-à-jour enamel vodka cups, Pavel Ovchinnikov, Moscow, 1908-1918, Freeman’s Silver, Objets de Vertu & Russian Works of Art, 18 October 2016, Lot 102. Photo Freeman’s, Philadelphia,

For this procedure, there are two methods different from the one described by Cellini. The most common and reliable one consists of removing from the object all the surfaces which are to receive the enamel, thus leaving only the partitions separating the different enamels or forming the contours of the design. Large areas of enamel and spaces with unduly acute angles should be avoided if possible, and large areas of metal should not be left amidst the perforated enamel. Owing to the difference of dilatation between metal and enamel at the time of baking, the metal surfaces will retract and the adjacent areas will be liable to split. The partitions of the contours are first covered with enamel and baked and the enamel then continues to be placed along the edges. The empty area will shrink with each firing and will be completely filled by the end of the operation. On relatively large objects in which the spaces between the partitions are considerable, a plaquette of the purest gold of the thickness of a sheet of letter-paper is placed under the object. This base is removed when the work is completed. Since very thick enamel is extremely dark-coloured, the space is first filled with flux and the coloured enamel is not applied until the last baking.

The second method of making perforated enamel is as follows: let us assume that we want to enamel a «charka»:we begin by forming the shape of a charkain red copper. This object is then covered with a fine film of pure gold or silver on which the contour of the partition design is fixed, as for cloisonné.

After covering this with enamel, the whole copper base is removed with nitric acid and the gold film is also removed, thus leaving only a very fragile enameled object, with only the gold line of the design in- crusted inside. It will be readily understood that this work requires great experience and care; indeed, the technique quite often does not succeed, even in the hands of very experienced persons.

On completing the work, it is sometimes wished to produce a matt enamel surface. To this end, the object is placed in a fluoride acid solution, which may be found in the trade and is known as matt enamel. Two more types of enamel production – bas-relief and painted enamel – remain to be examined. These processes enable us to utilize all the potentialities of enamel and to obtain the most complicated effects. Indeed, in both cloisonnéand champlevéwhat is available to the craftsman is essentially limited to flat surfaces, and reliefs can only be very slight and may prove to be incongruous.

Other possibilities therefore had to be found for the introduction of relief into enamel production, and this was done successfully by using bas-reliefenamel.

BAS-RELIEF ENAMEL

A metal bas-relief is prepared, with a low relief similar to that of a medal. It is covered with different enamels, in this case without separation by partitions.

To prevent the enamels from mixing together, a small quantity of tragacanth gum is added to the water. The procedure is simple, but its utilization requires a great deal of care in placing the different enamels and calculating the baking time so that certain enamels are not burned and in the timely application of white enamel to be covered later with coloured enamel; it is by no means easy to amalgamate the different colours, and the main guarantee of success is to work exclusively with experienced enamellers.

PAINTED ENAMEL

To succeed in painting enamel, it is essential, first of all, to prepare carefully the metal plate intended for enameling, secondly to use reliable and already tested enamels and thirdly to maintain absolute cleanliness. The metal used for painted enamel is generally copper and occasionally gold.

The plate is prepared as follows:

A metal sheet of the required dimensions and about half a millimeter thick is heated to a dark red colour and placed on an absolutely flat steel plate.

A hammer with one rounded end is used to forge the metal sheet in such a way that the hammer strokes form a complete spiral, beginning at the center and ending at the edges.

The operation is repeated several times and the sheet is reheated after each forging. By the end, the sheet should be slightly convex, but all its edges must touch the surface of the steel plate. After forging the sheet is cleaned with a nitric solution (12 parts water and one part acid) and washed thoroughly before enameling.

As stated above, the enamel is spread on all sides, to avoid warping of the sheet. One begins with the counter-enamel by adding a little tragacanth to it. The enamel should be applied as regularly as possible. Once the whole surface is covered, the excess water should be removed with blotting-paper.

The enamel applied to the front side should contain no tragacanth. When the sheet is dry enough, it is baked in an oven, from which it should emerge completely vitrified. If the surface shows any irregularities, some enamel must be applied where necessary and the sheet must be baked again. A sheet prepared in this way is ready for painting.

To convey the contour of the design to the plaquette, the tracing is lined with transfer paper rubbed with sanguine for a dark background and with chalk for the lighter parts. The contrasts are then surrounded with paint diluted with lavender oil, and baked.

If the composition includes sequins, they are inserted during this first baking; after they have been fixed, they may be touched up by irisations or by other colours. A fine layer of transparent enamel is then applied and the object is baked after each application following baking until the desired colour is obtained.

At that point, the figures and all the relevant parts of the design may be covered with white enamel, on the good quality of which the success of the operation entirely depends. For use, this enamel is rubbed on to matt glass with different essences – lavender or clove oil or condensed turpentine.

The modelling of the design is obtained by manipulating the transparency of this enamel through the application of successive layers. The enamel is applied with a small brush, more thickly for colours and more and more thinly for halftones and shadows. These operations are repeated until the desired result is obtained, baking after each layer.

PAINTING ON ENAMEL

As a final touch, coloured paint or gold may be applied lightly where necessary; in such cases, the gold is rubbed on to a glass surface with borax and bismuth in nitric acid, applied with a brush and lightly baked.

This differs only slightly from painting on porcelain. Concentrated turpentine with a little lavender oil is the favorite mixture for diluting coloured paint, which should not be applied too thickly and must be completely dried until all the essences evaporate.

More intense colours should be used for painting, because of the burning suffered by the paint when flux is applied.

The last layer of flux is placed when the painting is completely finished and baked. The flux must be easily melted and especially prepared for painting.

POLISHING ENAMEL

Polishing is mostly used for champlevé and cloisonné enamels, but also sometimes for painting on enamel covered with flux.

As we have said in the case of champlevé, accumulated surplus enamel is removed with a file after baking and the enamel is trimmed until a smooth surface is obtained. After this operation, the object is slightly baked to obtain a glazed enamel. The best surface can be obtained by polishing the enamel by means of a grinder with water and a fine pumice-stone powder. All our research has shown that the procedures of enamel use can be applied simultaneously and that the intelligent combination of these processes will bring about the beauty and harmony of the whole.

Franz Birbaum, December 1904