التصوير الزيتي ٤_a , من كتاب تكنولوجيا التصوير , د.م محمد حماد

As for the finest cardboard and drawing boards that are sold in shops specialized in the sale of fine art tools, they may help in doing some quick works or sketches and experiments for drawing, but they cannot in all cases be the true medium that the artist who wants to do work must adhere to. He writes eternity over the days and years..

The following is an explanation of the methods of preparing the different types that are used as a medium for oil painting.

1- Types of fabric and its preparation:

And it must be prepared in order to prepare the surface of the cloth for painting: as it is not possible to paint directly on the cloth, because the fibers, if we paint directly on them, are saturated with oil and color, which works to quickly erode and spoil them after the oil dries and hardens ... especially since the impurities that are found in killing the fabric may be It has a bad effect on the color itself. Also, those colors with which the fabric is saturated and intertwined in the fibers are difficult to repair or change the fabric if it is worn out and we want to restore it, because the colors in this case cannot be extracted from the surface of the cloth from which the cloth is made.

As for preparing paintings for oil painting, there are several methods that have been followed, all of which are basically consistent, which is an attempt to cover the surface of the painting with a layer of liquid that is superimposed on it so that it is suitable for drawing on it, and at the same time it prevents moisture from the painting, and accepts the spread so that this layer is not an insulating material that isolates the layer of colors About the cloth or the medium used for drawing.. At the same time, this layer should not be solid, but the cloth must retain its flexibility after being prepared, and this is one of the characteristics of a well-prepared cloth (1).

Therefore, it is not correct for the photographic canvas to be improperly prepared, so a thick layer of paint composed of a large amount of glue and powdered metal materials is placed on it.. because this paint is affected by water and is liable to spread with moisture that spoils it and makes it an insulating layer that separates the colors of the image from the texture of the cloth. However, in spite of that, many prepare the cloth by covering it with a layer of a warm solution prepared from liquid rabbit glue and water at a ratio of 1:20 by weight, with addition of sage, zinc oxide, or kaolin to the appropriate extent. After it dries, its surface is painted with a mixture of flax oil and vegetable turpentine in an equal proportion. Thus, the linseed oil permeates the surface of the painting and reaches the canvas itself.

There is a similar method for preparing the cloth, starting with painting it with a solution of gelatin or glue and hot water in a ratio of 1:15 by weight. After the cloth has dried, re-paint it with a similar solution, add silage or zinc oxide to it, then leave it

(1) To test the flexibility of the cloth prepared for drawing, a part of it is folded, and if the surface of the cloth does not crack or is affected by this movement, then the cloth is well prepared. And I remember that the first experience that I saw of this choice occurred when I was with my teacher to buy a canvas for drawing, and it was of a kind prepared in the factories of Louvre, France. When it is appropriate to use it:
Let it dry.. Here it is applied with a third layer consisting of turpentine and olive oil in equal proportions, with the addition of zinc oxide and any other color that breaks the sharpness of the white color. Some people are innocent of not using animal materials that are susceptible to water evaporation and being affected by moisture. Therefore, they prefer to use casein - which is used in some cases as fur. Also, when preparing the surface of the painting, they add to this liquid an amount of the Prophet's linseed oil. The surface of the cloth is covered with this liquid several times.

This is in terms of the outer surface of the painting. As for the back surface of the canvas, most artists leave it without any preparation so that there is room for direct ventilation. However, some artists prefer to cover the back surface of the canvas with a light layer of pure linseed oil and turpentine in a ratio of 1: 2 with the addition of a little white powder. Silver or kaolin, to maintain the cloth from the back. In all methods, when preparing the canvas using the previous methods, it is necessary to make sure that the canvas is suitable for the studio and its ability to be saturated with oil, so that it is a good medium that is suitable for drawing on.

After preparing the canvas, it is important for the photographer to stretch the canvas and fix it on the special frame, in which certain features must be available in terms of the type of wood, its fine artistic craftsmanship, and its suitability to the shape of the required frame (Fig. 57), whether ordinary or unusual shapes.

Figure (57) models of canvas stretching frames in unusual shapes such as octagons and oval shapes.
Figure 58

(1) The wood used for the manufacture of the frame must be of a good and strong type, and it is preferable to use old wood that is completely dry so that it will not be warped (killed) after

Installing and stretching the fabric on it

(b) The best types of musky, beech and walnut wood.

(C) The painting must be screwed to the frame in the usual way, and the shape of the frame is suitable for the shape of the required image, whether it is in the form of a square, rectangle, round, or oval...etc. (Fig. 57) The corners are also well-made, and keys are used for them, which are usually of a type Strong woods such as beech and hornbeam, through which the fabric can be stretched.

The connection of the corners is by the method of interlocking with the tongues so that the keys can be installed in them to move the ribs of the frame outward or inward ... Thus, the tension of the fabric can be controlled and adjusted if it expands or shrinks from the effect of summer heat or winter cold (Fig. 58) and you notice that in the tires The big one is the two-tongue interlock (Fig. 59). Also, in large frames, it must be supported by a medium beam or more, and beams can be installed in the corners, with keys always used to interlock the corners in accordance with the size of the panel (Fig. (60).

A) The edge of the inner frame’s ribs is inclined inward, so that the effect of the edge of the ribs does not appear on the fabric from the effect of any pressure on the surface of the fabric, and we see in (Fig. Which appears on the surface of the canvas from the effect of the sharp edges of the frame.

Figure (61) The ribs of the frame are inclined inward so that no effect appears

Its edge on the cloth after stretching it..

Resgel (62) The marks that appear on the surface of the canvas if the edge of the frame ribs is sharp.

As for tightening the fabric, it must be done lightly and accurately. With regard to fabrics with large dimensions, which must be carried afterwards to move them to another place, it is necessary to use fabrics on frames that can be folded by means of hinges. The part drawn on the outer layer, and wrapped around a cylinder of wood or cardboard to carry it to the place to be transferred. In the end, there is nothing left but fixing it on the final frame (chassis) by means of a pliers or special pliers to tighten the canvas. It is like regular pliers, but its end is equipped with teeth to hold the lapels of the canvas. With regard to the process of fixing the fabric with nails on the chassis, it is better to place strips of cardboard, paper moistened with petrol or aqua regia, or strips of tin on the tensile supports, so that the glue, when it penetrates into the fabric, does not stick to the wood, which causes some distress if necessary. The command is to remove the cloth and remove it from the frame (the chassis). Also, choosing the type of nails is very important, especially since in some cases it is necessary to move the fabric from the frame that is screwed on. It is always advisable to use long fine screws, first screwing into the frame up to its middle, and then screwing an aqua ragia