المواد الملونة ومواد الطلاء السميك ٢_a , من كتاب تكنولوجيا التصوير , د.م محمد حماد

With the sulfuric atmosphere, but it needs a great skill in its manufacture to estimate the percentage of cadmium in the composition, as the stability of this color depends on it.

Cadmium yellow is used pure or mixed with cobalt blue, which gives it greater stability... However, care must be taken not to mix it with terracotta colors, red, Indian yellow, vermilion red, cobalt violet, ivory black, viznese green, tabouli yellow, and chrome, as well as with silver white and all colors in which lead is included. And if the color is used purely, it dries in ten days.

(d) Chromium yellow * Giallo di cromo, which is an industrial compound of lead chromate (Cr 42), prepared by the reaction of lead acetate solution and potash chromate, so that lead chromate precipitates. It has different shades, including light, medium, dark, lemon and orange. The coloring power of this dye and its prevention of light is high. It is used in bright paints, but it blackens with heat and in a sulfuric atmosphere, and it is not good to mix it with alkalis, because its color turns red and turns into Ahmad Karumi lead... Therefore, it is said about this color that it is not true because of its lack of stability and its effect on light, and it also darkens as it ages, and for this reason many artists They prefer to use cadmium yellow shades, as they are more tolerable and stable, and can give almost the same effect, and if the chrome color is used purely, it dries in about seven days.

(e) Neapolitan yellow * Giallo di Napoli, which is a compound of lead antimonates, and has different shades, which are light yellow, dark yellow, and reddish. It is one of the delicate colors that were used a lot in ancient times to enhance light colors. Many manufacturers have adulterated it with cadmium yellow, ocher yellow, and zinc white, in order to obtain strong colors that have the advantage of stability and survival... As the smallest Naples changes if mixed with marine blue (or tarmir) or Veronese green, and colors that contain chrome or zinc in their composition Or cadmium or iron, and if a pure Neapolitan yellow color is used, it dries up after ten days.

) and (mart yellow **** Giallo di Matre, which is deposited iron oxide. The pigment of this color has different degrees, including light, medium, dark, and orange. It is very similar to the natural spina clay, and it is considered one of the colors of the artificial aukr or kite, and it is also stable and the only one Its quality depends on the purity of its composite materials, and it can be mixed with white and other fixed colors.

(g) Giallo di cobalto cobalt yellow, and it is called light yellow, and its coloration and light-blocking power are high, and it prevails in heat and in a sulfuric atmosphere. If it is prepared well, it has a high degree of resistance, and it is easy to mix with water or oil. It is good to mix it with cobalt blue, so it will be a beautiful, bright color, and when mixed with madder red, it will be a wonderful orange color. And clear color with oil
It dries after five days
Giallo oltremare (h) yellow tamarine * It is a compound of barium chromate, and artists are always advised to avoid using it because it is not a stable color. If this color is used purely, it dries in about a year.

It is composite

(i) Giallo di stronziana yellow

It is a strontium chromate, and the color is pure if it is dissolved in an acid solution

20% oxalic. Artists are always advised to avoid using it because it is not a fixed color. If this color is used purely, it dries in six days. (J) Zinc yellow * Zinc yellow, which is made up of zinc chromate (X) CR 41) and it is a lemon yellow dye that is less than chrome yellow. In finishing layers, it is an anti-rust pigment such as earth alkali chromate (calcium and barium). Its color varies according to the amount of zinc oxide it contains, and zinc green is derived from it when mixed with Prussian blue. It is one of the colors of weak resistance, and if it is used purely, it dries in about a year, in the days of Giallo di zinco as well, and it works

Giallo brillante (K) bright yellow *** It is a color of zinc and cadmium sulfate, and its shades vary from light, dark, and reddish. If this color is used purely, it dries in about six days.

(l) Indian yellow *** Giallo indiano, which is one of the fixed natural colors, and its color is a warm golden yellow. It was called Indian yellow because it was imported from India, and it is believed that it is extracted from the resin of some trees there, and it was possible to synthesize it chemically from euxantinic acid and oxide Manesia, however, chemically prepared dyes are not equal in their stability and resistance to light, the natural dye is expensive due to its rarity, and it is used in watercolors, and its covering strength decreases when mixed with oil. And if the color is used purely, it dries in 18 days.

Giallo vegetale (m) Lac yellow * La galla or madder yellow, which is one of the organic plant colours, therefore it is called vegetable yellow and the shades of lac yellow are not very diverse. We notice that this color does not withstand the effects of light, as it is an unstable dye in yellow color, and it combines with materials that have no color and do not interact chemically, such as aluminum hydrates. But because lacquer is an unstable color, it is not used much, and artists are always advised not to use it. And if the color is used purely, it dries in 40 days.

(R) Stil de Grain * Stil de grain This organic dye is called Grana de Avigny and it is extracted from plants that grow in some countries in the Mediterranean basin or something similar, such as France, Spain, Turkey and Iran. The degrees of this color vary from light, dark, and transparent golden yellow, and its degree depends on the amount of mixing it with Grana di Avignone materials.
Others that are added to it, such as soda, tar, crystallized salts, and calcium carbonate. And because this color does not withstand the effects of light, most artists are advised to use fixed colors that give the same effect instead. If this color is used purely, it dries in about eight days

Red dyes:

Red dyes are usually divided into three categories: natural and industrial iron compounds, non-ferrous industrial mineral compounds, and then red lacquer colors.

(1) Red Ocra *** Ocra rossa, which is actually a kind of ocher or red clay soil that is composed of iron oxide H 2 um, and it is found in nature in two types. At 5,200 and 5,500 degrees, it loses its water and turns into red ocher or red ocher, which is a strong, stable reddish-brown color, including English red, Rosso di Venezia red, and Indian red Rosso indiano... All of these colors are from natural iron oxides that are characterized by being intense. The possibility of its resistance to weather factors, and the strength of its coloring varies according to the length of the acidification period... It also resists the elements of corrosion, as it is like temptations with large, heterogeneous granules, and its ability to prevent the penetration of light is medium. Rosso english

As for the second type of red ochre dyes, which are composed of iron oxide, they are found in nature in a non-financial form, and they accept mixing with all colors, especially white colors, but with the exception of Neapolitan yellow or even cobalt violet. It takes eight days for the red ocher to dry if it is used pure.

(B) Red **** Rosso di Marte, which is a kind of industrial ocher consisting of iron oxide and aluminum and obtained by calcination of iron and aluminum hydroxide is yellow (marte), which is a strong and highly durable color. The color, if used pure, dries in about eight days

Rosso terra di Sienna Bruciata (c) Spina clay red *** It is one of the natural colors and is found in the form of calcified clay of iron oxide and manganese and its color is reddish-brown. It is one of the fixed colors and is not affected by mixing it with other colours, especially the white colours, with the exception of the metallic blue, Prussian and chrome yellow colours. If the color is used clear, it dries in eight days

Caput Mortum (D) Caput Mortum *** It is one of the industrial iron compounds and it is composed of iron oxide, and it is reddish-brown to violet, and it is one of the strong, solid dyes like iron oxides that get wet with oils with difficulty, and it is not affected by heat. If this color is used pure, it dries in about 12 days