الزيوت والراتنجات والمواد الأسفلتية ٢_a , من كتاب تكنولوجيا التصوير د.م محمد حماد

It tends to be greenish brown, and has the properties of saccateif in fast drying and cohesive strength.

As for its purification and refining, it is customary to use the same methods previously explained to treat linseed oil... However, some artists prefer to use another method in treating this oil. This method is summarized in putting walnut oil in an uncolored glass container with a narrow neck, and it is closed with a tight cork stopper, then left for a long time exposed to sunlight, then the oil is poured into another container slightly larger to accommodate a quantity of water and clean, soft sand free from loose materials or dust. . The large vessel - containing oil, water and sand - is shaken vigorously, then placed again in the sun... provided that the shaking process is repeated every day and put back in the sun for a period of not less than a week, then it is left until the sand separates from the oil and settles at the bottom. In this case, the color of the oil will become transparent and sticky (and it is called) (refined). Here, the oil is left for a few days to calm down and all the impurities are concentrated at the bottom... At the end, it is diluted in another container or filtered through a piece of linen, and thus it is prepared for use and packed in small bottles that are tightly closed.

Poppy oil:

This oil is extracted from poppy seeds, which are small black seeds of the poppy plant known as Papaverum Somniferum. The poppy plant is grown in the eastern countries with a moderate climate and the countries of Central Europe, and its use has been known since ancient times.

You will notice that the poppy seed oil extracted from the first pressing (first harvest) is almost colorless... As for the oil extracted from the second pressing, it has a somewhat dark color, and therefore it is preferable to use the first type over the second. We note that this oil has an oily smell. Almonds, and as for its fatty properties, it is lukewarm to its lack, and it is similar to siccate in its speed of drying and the strength of its cohesion... And the lack of color or transparency of poppy oil makes it suitable for industry. Colors to prepare pastes from... for light colors and white colors in general, and zinc white in particular... because the tendency of other oils to yellow may affect the sensitivity of white when used in the manufacture of photographic colors.

The light blue color is also one of the delicate or delicate colors, and therefore many painters prefer to use poppy oil in its preparation, believing that it prevents yellowing of the colors that are used in its composition or preparation... Therefore, the colors do not lose the degree that the artist intended for these colors to be. .

To purify the color of this oil and make it usable, it is advisable
Especially from this, we see that each of these three types of oils previously mentioned, flaxseed oil, walnut oil, and poppy oil, has a feature that distinguishes it. And all of them are used in the preparation of colors so that the fatty properties characteristic of each type of the three oils can be exploited in accordance with the nature of the color to be prepared... Despite this, many artists, when preparing their colors, saw that the cold-processed linseed oil, whose preparation process took more or less Refining and purifying it for a long period of time (about six months) is the best type of oil for photography. Therefore, they prefer to stay away from other oils - as much as possible, and when preparing colors, they should avoid using varnishes, volatile oils, and other chemical products. Equipped for painting and decoration, which are not suitable for oil painting, especially in classic works that are intended to have artistic value at a high level throughout the ages.

Follow those methods and methods that were used in the treatment of linseed oil, as we have previously explained.

volatile oils

Pinus pinea Pinus maritima 1 - Vegetable turpentine: It is an oil that quickly evaporates (from volatile oils) and is extracted from the stems of pine trees. It is always known by the place in which it was used and the type of tree extracted from it... Therefore, it has many names. We find, for example, Strasbourg turpentine oil (which is extracted from Pines Benia trees) and turpentine oil (Venice) produced from Pinus larix trees, as well as Bordeaux turpentine oil from Pines Maritima trees...etc. Note that Pines are needle-leaved pine trees.

Volatile oils, some of which are natural, such as vegetable turpentine, and some of which are mineral oils, which are extracted from petroleum. They are explained as follows:

There are other types of turpentine oils that are extracted from the leaves of different plants, such as the leaves of Schinus terebentifolia, which is colloquially known as broad-leaved pepper.

Turpentine oil is also extracted from the peels of the fruits of trees, such as the mango tree, Mangifera indica, from which man smells the smell of turpentine in the peels of its fruits. In India, turpentine oil is extracted from the peels of these fruits. This oil is also extracted from the pulp of the fruits of some trees, such as the fruits of the pistachio tree. Pistacia palistina and its hard fruits have a pulp like a nut and contain turpentine.

Of all these different vegetable oils, we find that Venice turpentine is the best for the artist because it is suitable for oil painting
Vibert ... 2- Industrial or mineral turpentine: It is a petroleum product and is widely used as a solvent or color thinner, due to its cheap price, although it is better to reduce the use of volatile oils, especially mineral ones. As diluents to dilute the color - as much as possible, because these volatile oils, no matter how pure they are and do not leave residues or residues, have a serious defect, which is that they thicken the thickness and density of the colors in relation to the medium, and make them opaque or matte (matte) and give the drawing a kind of dryness. It also makes the colors unstable, and some weather factors may affect them. In particular, mineral turpentine oil (essence) made from petroleum materials and refined by vibrating is recommended not to be used as much as possible, for the aforementioned reasons, in addition to the difficulty of keeping it pure because it contains impurities, sulfuric acid and Vaseline ... which affects the used oils and the colors consisting of oxides. Mineral, as a chemical reaction takes place in it, which beautifies the colors of the drawing, blackens and makes it difficult to return them to their original value... Therefore, we can decide that it is not appropriate to use these volatile oils in oil painting as much as possible, and it is advisable to use flax oil and walnut oil, as it has been proven with experience Long artists are the best solvents that can be added to oil colors to lighten them... which are actually used in the preparation of colors. As for those who want fluidity and smoothness of colors, they can use a mixture of two parts of flax oil (unboiled and well purified) or walnut oil with one part of very pure vegetable turpentine (1).

Dried oils

Dried oils (made of mineral salts of organic acids called driers) are added to oils that can dry out and oil colors to reduce their drying time. These oils used in photography as dried oils are usually prepared by boiling the oil with some oxygen-rich substances such as lead oxide (charging), borax, or acid salts. Naphthenic such as cobalt naphthenate, lead and manganese naphthenate dissolves in oil, so its drying speed increases, and calcium resins can be added to it to increase its gloss.The oil colors dry after the oil absorbs a sufficient amount of oxygen in the air, and thus the oil turns into a solid layer that is heavier and more treacherous. ....

Dried oils are also produced from salts that have resinous qualities, such as rhododendron, zinc, or copper, all of which are derived from rosin. It is easy to prepare by melting rosin in aluminum containers at a high temperature.

(1) In order to use trientine vegetable oil in artistic photography, it must be of a high degree of purity, transparency, and colorless, and to test that, we put a drop of it on a paper that absorbs or paper that is translucent, and if it evaporates quickly without leaving any trace on the paper, this indicates the purity of turpentine. Vegetarian .. Also, the use of mineral turpentine oil extracted from petroleum should be avoided, because it affects the drawing, as we have previously explained, and may add yellowness to the picture, because it is not strong.