التصوير بألوان التمبرا أو الجواش ١_a , من كتاب تكنولوجيا التصوير ، د.م محمد حماد

1- Painting with tempera or gouache colors - Tempera colors are tinted colors that are not transparent, and have a great ability to cover the surface of the painting or the medium on which it is painted... This is unlike the regular transparent water colors that dissolve in water and can be painted with on paper for drawing. without preparation. As for opaque tempera colors, they are prepared by mixing them with an aqueous adhesive medium (from materials that dissolve in water), such as natural resinous materials such as gum arabic (from which the colors prepared are called guazzo) or animal slimy materials such as rabbit glue, fish glue, or regular glue from horns and hooves animals, or egg whites. Or from mineral substances such as wax melted in a volatile perfume such as turpentine (and we note that wax there are two types of it, animal wax, which is beeswax, and mineral wax from petroleum extracts. Likewise, turpentine, which is vegetable and mineral). Eggs have been used as adhesive or color fixing media in ancient Egyptian history. The archaeologist, Asbrel, found a gum that he defined as Arabic gum that was used as a medium for painting colors in the Eighteenth Dynasty. It is also mentioned that several bags of paint were found containing a thick layer of glue flat on top of the color. It was deposited at the bottom in bags whose contents had not been exposed to the atmosphere. The glue was also used in the depiction of King Akhenaten and the drawings of the little princesses. It was also used on parts of the colored floor. The Egyptians extracted glue from bones, skins, and cartilage by extracting it with boiling water, then concentrating it by evaporation, then pouring it into molds to cool it and turn it into a solid. It has been used in the formation of gypsum mortar (glue and limestone powder), and it has been used as a mediator or color fixer since the Fourth Dynasty. Toch also believes that the glue was used in the drawings of the Barnab tomb of the Fifth Dynasty, and it may also have been used to paint furniture or the surface of the wall, whether it was made of plaster or stone, in order to block the pores before painting.

Some scholars believe that the Egyptians used white albumen (whiteness) as a mediator or adhesive in ancient Egyptian photography from the Fourth Dynasty until the end of Roman rule. Some also see that Al-Masry painted the surfaces of stones and plaster used as a medium for photography, in order to close the pores before drawing on them, and it is not excluded that Al-Masry used both methods. And I mention here that the Kamose painting that I found in Karnak had traces of red and light blue colors during its detection, and the trace of these colors was lost after the Authority used water to clean it, which is likely that it was fixed with a resin. I also noticed that some of Akhenaten's colored stones, which were exposed to the atmosphere, were not affected by the rain water, which made me prefer the use of egg albumen in their composition. Thus, we can determine that the colors of tempera, whether mediated by glue, glue or albumen, were known in ancient Egypt and were used in depicting most of the Egyptian images that were found on the walls of temples and tombs and on wood, papyrus, leather and fabrics that were used to cover the dead, and to make masks and coffins for mummies. And it was made of reinforced layers of linen and plaster or remnants of papyrus and plaster, and these coffins and masks were colored with tempera colors after preparing the last surface with a layer of soft gypsum to be colored or covered with gold leaf, especially over the faces of mummies. It is still used in many works of art so far. • Of any kind of color. Humidity and its effect on colors: One of the apparent examples of the effect of moisture on works of art is the tomb of “Nefer Tari” in Luxor, as moisture leaked into it after its discovery and salts appeared on the inner walls, which caused corruption and expulsion of colors. Walls from the source of moisture and cleaned of salts and then treated. Therefore, here we must mention that the wall must be safe and free of moisture before working on preparing it for painting. In order to ensure that the wall is free from salts and moisture, we take into account the following: (a) The distances of the walls to be painted with tempera from sources of water and moisture that can seep into them from the foundations or from the walls adjacent to the water sources or from the upper courses that are filtered by water in the lower floors, etc., so that they are not carried into them. Salts that have a harmful effect on wall drawings and their colors (b) The painted wall can be isolated from water sources by one of the methods of isolation known in architecture, such as making an insulating layer of asphalt, white silica, or lead panels, or building a secondary wall with a width of half a brick or a brick for drawing on it in the case of buildings The new ones, or the old drawings are transferred to it in the case of the drawings that have an antique value and are intended to be kept in their place or any other place to which they are transferred

(C) In the event that some water leaks from the foundations into the painted wall, the foundations can be sacked and new foundations made completely isolated from the water. About a cm and reach the middle of the wall, so that the moisture escapes from inside the wall to the outside and does not seep to the surface of the wall (Fig. 24) in simple cases. Or the openings of these pipes are covered with a covering wooden or metal button, and it allows the wall to be vented. Traces of salts on its surface after drying. Of course, this is to ensure that the walls prepared for the drawings are free of salts • As the appearance of salts in the wall affects the colors used in wall photography and affects them if they crystallize on their outer surface, then the colors spoil and erode the surface of the whiteness. Also, the appearance of these salts under the surface of the color layer works to separate it from the surface of the wall in the places where it crystallizes. Preparation of the surface in the past: I followed several methods to prepare the surface to be painted on with tempera, so the walls were treated with whiteness. The whiteness used in ancient Egypt consisted of two basic materials, clay and gypsum

(1) Clay - The use of the whiteness of clay dates back to pre-dynastic and early dynastic eras. Its types vary according to the materials that make it up... But in general, we can say that we notice that there is a kind of coarse mortar or whiteness that is mixed with hay, and it consists of ordinary Nile silt, which is a mixture of clay and sand in varying proportions, with a natural amount of calcium carbonate (carbonate of lime). And a small percentage of gypsum sometimes. As for the second type, it is better and gives the mortar a smooth surface. It is a soft natural mixture of clay and limestone, and it is found in cavities and pockets on the slopes of hills and backlands that were swept away by the stormy rains that fell on them. (b) Gypsum. As for the whiteness of gypsum, it was also used in ancient Egypt, especially in leveling the surfaces of the walls of houses, palaces, tombs, and temples, and their ceilings, to create surfaces suitable for photography. The clay was usually covered with the whiteness of gypsum, and in the absence of using clay mortar, the gypsum was used to cover up the defects and irregularities in the surfaces of the stone in order to level its surface before photographing it. From this we see that gypsum is a material that was known in Egypt since ancient times, and it is believed that the name gypsum is taken from the name of ancient Egypt, which was debated in European languages, so he pronounced “ajibt” as we mentioned previously. This substance is found in different parts of Egypt, such as the desert near the Red Sea coast, between Ismailia and Suez, in the Lake Mariout area, west of Alexandria, in Fayoum, Maasara, and Abu Rawash - (Egypt). Chemically, gypsum is a crystalline substance composed of calcium sulfate crystals (lime sulfate). Aqueous, i.e. containing water and completely united with it (2 kb 20 yd a) and gypsum is very similar in appearance to alabaster (calcite), which is calcium carbonate. Gypsum is often called Marmara. By heating gypsum to a temperature between 100 and 130 degrees Celsius, gypsum loses about three-quarters of its crystalline substance, and a substance is formed from it that has the property of returning to union with water, so it becomes a solidified substance and eventually becomes very solid. The calcined material in its pure form, which is manufactured in Europe, is known as Plaster of Paris