During their visits to the Narodna galerija, Ljubljana, school children ask various questions. Explanations of the museum educator help them to become aware of the Invisible Sides of Visible Art, as our present presentation, the result of their inquisitive questions, is entitled. The CD ROM is a careful documentation of the exhibition in 1991 to be left after the show has been closed.
The distance of time has caused that many an invention of past masters is overlooked today. Thus, we are trying here to show the children the "history" of a work of art: what the process of creating old masterpieces was like and why they look as they do nowadays.
Every work of art is designed for a special medium; painters and sculptors, according to their knowledge and sensitivity to materials and tools, choose those that are best suited to their expressive purpose. A whole spectrum of different tools and materials are available to artists nowadays. But was it so in the past as well?
Ancient masters employed natural pigments with great care because they were not easily available and some of them were extremely expensive. The famous German artist, Albrecht Dürer, for example, paid for lapis lazuli by an equal weight of gold. These masters were also thoroughly familiar with natural materials because they lived in close touch with nature. They did not work under the pressure of time and they left every material its due time to get ripe. Their masterpieces were executed very patiently and carefully, so they could defy time and can still be admired today. A workshop of a medieval master had nothing in common with a studio of a modern painter or sculptor. A medieval master was usually not skilled only in painting or sculpture, but also in some other crafts; there were several apprentices in his workshop to be trained in different skills. First they had to perform simple minor works, like grinding colours, and only later they were entrusted with more difficult tasks.
The first part of the catalogue deals with painting techniques. We begin with a medieval fresco and explain the introductory stages in the process of its creation (graphic design it was modelled on, cartoon). Only after preparations had been accomplished the fresco painter could start applying paints to fresh plaster. They were made from powdered pigments diluted with lime water. While plaster, together with paints, was drying, a chemical change took place which finally caused that pigments became an integral part of the surface. The durability of frescoes has been proved by their respectably old age.
By the l5th century, most of the paintings had been painted on wooden panels. Trees were felled in late autumn when they were not so rich in sap and the logs were divided into planks. After having been stored and seasoned, which took almost two years, the wooden support was prepared for painting in a workshop. The glue and gesso ground formed "a good bed for the painting", as it was written in a recipe by an Italian master several centuries ago. After that a preliminary underdrawing was sketched on the scraped and smooth ground. The areas to be gilded were covered with several layers of a binder-Armenian bole (clay pigmented by iron oxides) mixed with egg-white. Gold leaves were laid on this ground which had previously been wetted by white spirit or brandy to dissolve bole and adhere gold. The picture was painted then in egg tempera which had been the most common technique in panel painting all until the l5th century. The technique of painting in oils was developed in the first half of the l5th century by Dutch painters. Oil paint is made by mixing powdered pigments with linseed oil as the binder and turpentine as the diluent. In the beginning, oil paints were also applied to wooden panels, but wood is prone to infestation by woodworms, it easily cracks, and it can not be used for large-scale paintings, so it was soon substituted by canvas.
Quite often, various inscriptions and labels can be found on the reverse of the pictures. The information they offer helps us to find out where a certain picture might have been travelling during its history. Such "travels" could be very varied sometimes. In the course of time pictures often passed from one owner to another. They were bought, sold, and donated, while some of them were also stolen. Together with their owners, the pictures travelled from country to country, they survived wars and other disasters. One such case is demonstrated by a map where a route of a Pynas painting can be followed, and by a table where years and changes of owners and places are stated.
Like oil paints, paints used in watercolours were also made by artists themselves. They mixed finely ground pigments with gum arabic as the binder and water as the diluent. Watercolour painters soon noticed that thicker layers of colour substantially shrank and cracked if drying too quickly. To avoid this trouble they began to add honey, sugar or glycerin to the diluted gum substance. These media slowed down the evaporation and prevented the occurrence of cracks. A small quantity of purified ox gall was also added to the gum dilution to reduce the surface tension by its flexibility. In pastel crayons, which contain chalk and clay, powdered pigments are mixed with a small quantity of glue binder. Pastels excel in diversity which results from their great range of colour tints. Pastelists tend to achieve airy look and softness of their motives.
In the second part of the catalogue we present some drawing techniques. Drawing is the basis of all forms of Fine Arts. Charcoal, one of the oldest drawing media, has been known ever since the prehistoric man had first met with fire. It is produced from wood by excluding air while being burnt. Charcoal gives a special softness to drawings, resulting from the tiny particles of its structure. Pieces of certain rocks used by primitive man for drawing pictures on the walls of caves had been the forerunners of some drawing media. Their distant relatives are modern chalk crayons. They are made from finely ground pigments, mixed with wax or oil and shaped into sticks. Besides black chalk, white and red chalks have also been widely used. A pencil allows a considerable variety of expression as well. A skilled draughtsman can render a whole range of tones, from pale grey to deep black.
Bistre, sepia, Chinese ink and other inks belong to drawing fluids. The first three in particular were often employed in washed drawings. The artist used paint brush wetted by one of the mentioned diluted fluids and washed here and there the dried lines to get planes. Where he wanted his drawing to be in deeper shade or the objects to appear closer to the viewer he applied thicker dilution, and where he wanted it to look brighter and the objects to appear more distant he applied thinner dilution. Apprentices in painting workshops had to train their skill of drawing by making sketches after printed patterns. Later, students at the Fine Art schools also began their training by drawing after original works by old masters, and having mastered that, they advanced and could draw from life. We can conclude by saying that no work of art can be realised without the help of drawing. The third part of the catalogue deals with sculpture. Children can get acquainted with the difference between the features of a relief and a round statue first, then various techniques of sculpture are explained. Clay is the most commonly used modelling material which serves a sculptor to fix his first idea. If clay products should attain durability, they must be baked in a kiln. Baked clay is called terracotta. Some artists prefer their terracotta works to imitate the appearance of precious materials, so they change their natural colour by giving a paint finish to the statues. Most often black colour is chosen to imitate bronze. We have reconstructed modelling in clay as well as modelling in plaster of two previously existing works. First the sculptor made a wire skeleton which was kind of a "soul" of the future sculpture. The main idea of the work of art has already been solved by the construction of this armature. Sculptors must have a clear concept of the statue or composition they are going to make because later no essential alterations are possible. Dealing with wooden sculpture, we enumerate types of wood, most suitable for wood-carving. Carvers usually made their sculpture from a single piece of wood; but if the piece was not big enough, several pieces had to be joined together by means of wooden dowels. The joins were pasted over with fabric to prevent the possibility of later flaws. For the same reason the reverse of a sculpture was sometimes carved out and made hollow. In the course of centuries, wooden sculptures have been exposed to many different harmful effects. A frequent damage is caused by woodworms which occur above all in damp environment. Restorers often have to conserve wooden sculptures which are so badly wormeaten that wood dust comes pouring out of the numerous holes. To prevent further deterioration, chemical protective substances are injected into or gas applied to the riddled piece; then the unsolid wood is consolidated. Damage to sculptures has not only been caused by worms but often also by people. Old sculptures seemed out of date and awkward to people of later periods, so they had them cut by height and width; faces were often altered to suit the contemporary taste. The fashionably altered sculptures were then placed into new altars.
Some tools and equipment used in wood- and stone-carving are also presented. Then stone-carving techniques are explained and the importance of a plaster model for a final work in stone is demonstrated. We call children's attention to the technique of stone-carving in the past: sculptors drew the preliminary sketch on each of the four vertical sides of a stone block and then they slowly began to cut away the unwanted stone and the form was emerging gradually. They did not carve deep into the block but approached the final image of the statute step by step by carving evenly on the front, lateral and back sides, using ever more precise carving tools.