الزيوت والراتنجات والمواد الأسفلتية ٣_a , من كتاب تكنولوجيا التصوير د.م محمد حماد

Pistacia lentiscus and the most used type of resin in the varnish industry is the mastic resin, due to its ease of manufacture, and it is suitable for use in all artistic purposes. In addition to the price tag. It is a resinous substance that emerges from the roots of the turpentine trees, which usually grow in hot regions in Africa, Asia and America, by digging holes in the trunks of trees, and this resin flows out of them - in the form of small, light transparent lobes that tend to turn slightly yellow - and it is easy to dissolve in turpentine and linseed oil. It is a flexible, resistant and almost colorless varnish. It can be seen that all types of varnishes used in frills are usually made from this resin, and many types of final varnishes are also made from it. Here are some ways to prepare different types of varnishes:

The final surface of the image after making sure that all layers of the image's colors have obtained sufficient drying and hardness.

A - Mastic varnish

It is easy to prepare this varnish by placing the amount of mastic required to be made in a glass container (a vial of density as used for chemical purposes) (Fig. 73) and heated by a water bath to prevent ignition, then the amount of turpentine and linseed oil is added to it as required. We present here three compositions of this type of varnish that artists use now:

A

Figure (73) a used bottle

for chemical purposes.

(1) Mastic

250 g

380 g

Pure Venice turpentine

After dissolving, the solution is filtered with a linen cloth and then added

Pure flaxseed oil
And it is left to cool before the bottle is closed or its contents are transferred to containers.. This varnish can also be used for painting and touch-ups... Because if you want to draw on a painting after its colors have dried, its surface must be painted with a special varnish for touch-ups.

(B) Venice turpentine mastic, pure walnut oil

100 g

350 g

70 g

This varnish conveys the oily substance and is also used in the work of frills.

(C) mastic

170 g

510 g

Pure Venice turpentine

This varnish is of the quick-drying type, and is usually known as varnish. Its thickness can be reduced by adding part of the oil to it (depending on the purpose for which it is used) if it is used in photography to dissolve and mix the stubble.

Colors .

Vernice Magre

Dammar o Thamar varnish

Batavia and the damar material from which this varnish is made is a resinous resin extracted from plants that differ according to the regions in which they grow. We note that its resin is not elastic and is not suitable for kneading colors because it does not follow the regularity of drying colors. There are many types of Dammar varnish in the market, but the best of them is Batavia varnish. It is strong and solid and resists yellowing. It also crystallizes and gives the image a more beautiful luster than any other type of varnish. Its resistance to weathering is less than the aforementioned mastic varnish, but it is more pure. Its strength and hardness make it suitable as a final cornice, but it can also be used as a retouch cornice after adding linseed oil or walnut oil. We provide here two compositions of this varnish.

(A) Damar Mejza (of the Batavia model).

150 g

Pure Venice turpentine

350 g

Pure flaxseed oil

100 g

(b) dammar

100 g

Pure turpentine

400 g

Soak for a week, then drip twice with Kinan cloth, then add

Pure flaxseed oil

50 g
3- Ambra o Succino varnish

It is the most expensive and best type of varnish. Some people believed that amber was a magic compound that ancient photographers used to use as a varnish for pictures to double the brilliance of their colors. During this time, this fragile resinous substance was transformed into a solid, refractory, fossilized substance that is not affected by the atmosphere. As for its colors, it is yellowish brown, reddish, dirty white, or yellow.. The latter is the most suitable species for photography. This substance is melted at a high temperature in the oil and combines with it.. However, its manufacture requires a lot of precision, and therefore many artists do not try to manufacture it and consider it an industrial secret of the factories that produce it... Therefore, they keep its secrets.

The following is the normal composition of this varnish:

Put in a double-bottomed iron pot 12 parts of roasted amber with a little turpentine and heat until the amber dissolves, then add 12 parts of linseed or linseed oil, and if it is about to boil, mix completely and leave to cool, then put in containers of colored glass. This varnish is used to paint the surface of the final picture with a light layer after the color layers have completely dried, so the colors are completely saturated with it and unite with them and give it flexibility and strength and it is not hard or rough or liable to shatter and collapse.. It also gives it immunity against weather factors, and its oily properties make it

Slow drying and flexible, which helps to unify and regulate the drying of colors.

300 g

Copral, Sandraca e Cauccio varnish

Copal is made from a strong resin from trees growing in the islands of India, South America and Africa. For photography, strong, fossilized cobalt is used after being dissolved in oil or turpentine.

Here is an old installation of this varnish:

Copal clipped

Pure flaxseed oil

Pure turpentine

Raw wax (Alexandrian)

These ingredients are melted at a temperature above 5100 C.. Thus, cobalt varnish is produced, which is desirable to use for industrial purposes because it is not devoid of color. It also becomes darker in color whenever it is exposed to air. As for the other resins, which are sandros and caucio, they are also not recommended for use in varnishing artistic pictures, as they are non-sustainable materials.

100 g

350 g

100 g
Vernice dorate this and there are many other types of varnishes, such as gilding varnish, which has been used a lot since ancient times. It is usually made of mastic and a greasy mixture, and some bitumen, shadow mud, or natural or burnt sabna mud are added to it. Vernicenera d'Apelle varnish known as black Abelle varnish is made of mastic resin dissolved in pure turpentine to which bitumen is added.

For a long time, it is not suitable as a strong insulating layer with immunity, and therefore it is usually used for industrial purposes

And you notice that all kinds of varnishes prepared from alcohol, benzene or water are not suitable for artistic oil painting works due to their rapid dissolution and evaporation, and they cannot be used in mixing oil colors because they float on the surface of the mixture and form a non-uniform insulating layer.

Natural resins and asphalt materials (bituminous)

The ancient Egyptians knew the resin of rosin, and it was found used in the mummy of a monkey, but it was not possible to specify the name of the plant from which this resin was extracted, which is known to be from the coniferous plant family. Bitumen was also found used in embalming and spread during the Ptolemaic era, but it was not used in photography

And natural resins, including rhododendron and copal (Sandros), which are resinous oil extracts, ie solutions of resin in a volatile solvent, which are carried in the containers of some resinous trees. We will conclude the study in this chapter with a summary of asphalt materials, natural or industrial colloidal materials that are the flexible material in asphalt coatings and varnishes.

1- Rosinaria:

This substance is an extract of the essence of some resinous trees (such as pine trees, fir trees, etc.), and it can be extracted by stripping the resin-bearing containers in its cover (bark) and sometimes in its wood. The essence is a solution of rosin (70-80%) (in turpentine perfume) 20-30%) which is separated by dry distillation or by water vapor

As for the composition and properties of rosin, it is a yellow or brown resin, its density is 107 to 108, and it melts at a temperature of 570 to 580 degrees Celsius. It is soluble in most organic solvents, especially in alcohol and hydrocarbons such as benzene and oils. It is possible that rosin is the constituent material for many varnishes, but despite that it has the following disadvantages: It is a resin with a high degree of acidity because it consists of a mixture of four free resin acids of equal parts. Its elemental symbol is K20 YD 2130, the most important of which is