التصوير بطريقة الأفرسكو (الألوان الجيرية) ٢_a ، كتاب تكنولوجيا التصوير د.م محمد حماد

Talented.. and even messengers of reform who worked to serve humanity to believe in the power of God who created the world and created his creation

In this particular era, the Dutch Giovanni van Dyk discovered the technique of oil painting and introduced it to Italy by Antonello a Messina, but unfortunately, since this method worked and spread in Italy, the Italian artists neglected the Afrosque, and did not take care of it with the care that would ensure its continuity and survival.. so that was A reason for its decline and decline in the world. Then the matter got worse and worse when three eras of art took place in Italy, namely the Baroque, Rococo and Modern eras.

As for us in Egypt, this art remained in a state of stagnation and stagnation until God permitted some Egyptians to specialize in alfresco and returned to Egypt in the thirties. As his assistant in the implementation of two frescoes at the entrance to the Zoo in Giza when I started my work in the Buildings Department in 1938. Mr. Abdul Aziz Khaled Darwish has a painting “Aversak” in the Courts Complex, as well as the late Abdel Hady Al-Jazzar, another painting in the Courts Complex, which he designed after winning its competition. .

Search for the surface prepared as a carrier for photography:

The wall that will be used as a photographic stand must be examined to ensure that it is far from moisture and that it is free of salts, especially calcium salts that are soluble in water, such as calcium nitrate, calcium chloride, or sodium. These precautions that are taken here are the same as what we mentioned previously in preparing the walls for tempera in the previous chapter, and they are summed up in keeping the wall away from sources of moisture and salts with natural ventilation so that moisture does not cause salts to leak through the wall to the surface on which you want to paint and thus harm its inscriptions.

Prepare the materials needed for the mortar:

Since the mortar of Afrosk consisted of sand and lime, therefore, we had to take care of preparing these materials to be ready for work.

The sand used for lining must be of a clean type free of dust, clay and salts, and it must be fine sand that is sieved in a wire sieve whose openings are 1 millimeter. Therefore, the sand must be washed in a barrel, tank, or basin filled with water and stirred well, then the water is removed from it whenever it becomes dirty and filled with clean water. This process is repeated several times.
So that the water does not show any trace of salts or foreign materials, and here the sand is dried by the sun, and thus it is prepared for work

The strength of the fresco drawing and its effect on the surface is due to several chemical reactions, the result of which is the binding of the dyes to the surface of the whiteness on which it is painted, which consists of slaked lime, which lost its carbon dioxide gas when burned in the oven, then absorbed water.. and then when exposed to atmospheric air, it is absorbed Carbon dioxide gas gives us crystallized calcareous salts (calcium carbonate... which is the transparent crust that protects and stabilizes the colors. This also happens to the colors of clay and silicate... Its association with lime gives a substance similar in composition to that of cement, and this explains the hardness and resistance of afrosque.

And since the most important material in preparing the surface for the afrosque is lime (calcium hydroxide), so we must first review the method of its preparation, as it is produced from burning calcium carbonate (or) carbonate (lime) - which is the material of limestone or marble - to a degree equivalent to 800 to 1000 m approximately, and from this, quicklime is produced.

Calcium carbonate (marble) or limestone (limestone) at a temperature of 5800-1000 m

Calcium oxide (lime (lime) + carbon dioxide gas is given as KAM at a temperature of 5800-1000 C. It is given as A + KAB and the quicklime is quenched by sprinkling it with water, so slaked lime is produced with heat generated.. This slaked lime is what is used in the preparation of mortar From which whiteness works for the Persians

To prepare the colors used in his drawing (1).

From this slaked lime, what is known as lime zest (which is the very soft part of it) can be extracted by placing a quantity of slaked lime in a basin of water that submerges the lime, then we stir it and leave it to settle, after that the surface water can be changed several times by repeating this process with stirring for a week, then We leave it for a while, with which the coarse part settles at the bottom and is used in the normal whiteness (2) 0. As for the atom-fine part, it rises above the surface.

(1) Lime must be used after being prepared in this way within a period not exceeding four months from the beginning of the extinguishing process, because after the elapse of this long period, reactions have occurred in it that lose the most important element in it.

(2) Ordinary mortar is a mixture of hydrated lime powder and sifted sand to cover the walls. The ratio of lime to sand in the ordinary mortar is 1:2, but this ratio varies according to use. With the passage of time, the reaction takes place and the mortar that forms the mortar becomes stronger. The slurry can be known whether it is new or old in two ways, namely the litmus test method and the hydrochloric acid test method. (a) To test the slurry with litmus paper, put a piece of slurry in a test tube, add an appropriate amount of water to it, shake the tube, then dip the red litmus paper in it. If its color is blue, the slurry is fresh, and if it is not affected, the slurry is old.

(B) To test the mortar using the hydrochloric acid method, we put an amount of diluted acid on top

A piece of mortar, so if an eruption occurs and a gas rises that clouds the lime water, the mortar is old. And if it didn't happen

Foran was freshly grouted.

The first layer, which the craftsmen call butter (lime), is the one that is recommended to be used in the manufacture of mortar for preparing the surface on which to paint in fresco. As for the coarse part that is deposited in the lower layer, it is used in the types of ordinary mortar for building, but it is not used in the preparation of fresco as we mentioned. .

Lining Mortar Composition:

The lining mortar shall be made of lime filtered in the previous manner and sand previously prepared and sifted in a sieve whose holes are 1 millimeter, in a ratio of 1: 2, i.e. one part of lime and two parts of sand, provided that it is well mixed. It is noted that it is important before the whitening process to remove the dust on the walls, wash them and saturate them with water well before the splashing process, which is a necessary process for the whiteness to stick to the wall. After the splash, the period is five days in normal weather, then the lining is whitened over the splash and left to dry for three weeks as well, even if (the classical artists used to leave the white for a year to dry) and after that it becomes prepared to put the backing on top of it, which is the layer on which the fresco drawings will be made. Some artists are interested in washing the wall after splashing it several times and leaving it to dry after each time.

Composition of the backing mortar:

The backing mortar also consists of filtered lime (lime froth) and previously washed washed sand, which has been prepared and sieved in a sieve with a capacity of 1 mm, in a ratio of 1: 2, i.e. one part of lime and two parts of sand. This mortar is coated with the surface to be photographed on. When the mortar composed of lime is exposed And the sand is exposed to the air for a long time, that is, with the passage of time, the water evaporates and the mortar dough dries and becomes cohesive, and that is due to the reaction that takes place inside it - it is preferable to mix sand with it - as it makes it porous, and thus the carbon dioxide in the air can permeate the internal parts of the mortar and interact with slaked lime forming carbonates Calcium, which binds sand grains to each other, as well as to the bearing surface, and thus a coherent layer of mortar is formed on the bearing surface.We note that the backing mortar works with a thickness as small as possible (about (name) so that increasing its thickness is not a cause of cracking or falling off and the drawings are lost. ..