Polymetaal

PIGMENTS

Each pigment has specific characteristics which determine the final appearance of the colour. The pigments come from various sources: mineral or orgnaic, natural or synthetic. Most of the pigments are currently of synthetic origin (95%). In the 19th century synthetical mineral pigments were made. Synthetic organic pigments come from the petrochemical industry of the 20th century.

Colour Classification

Every pigment can be identified with the international Colour Index or Colour Code.

CHARACTERISTICS

YELLOWS AND ORANGES. All the yellows of the Charbonnel range are composed of azo pigments. These are organic pigments, with ,the oldest ones dating back to the beginning of the century. These pigments have medium colouring power and are well coloured. They are reasonably transparent and chemically stable.

REDS. The reds are composed of azo and quinacridone pigments.

The azo pigments are described above (see yellows). The quinacridones are very powerful and deep and have an excellent lightfast quality. They are very transparent.

VIOLETS. These pigments are composed of dioxazine and have the same characteristics as the quinacridones: they are very powerful and deep and have an excellent lightfast quality.

BLUES. Most blues are phthalocyanine pigments except for ultramarine (combination of aluminium and silicate) and Prussian blue (ferrous complex:).

The last two colours have a weak covering and colouring power: However, they have a very good lightfastness and are compatible with all the pigments. Phthalocyanine pigments are transparent, highly coloured and very stable.

GREENS. These pigments also have a phthalocyanine base and are transparent with a good colouring power and excellent stability.

EARTH PIGMENTS. These pigments have a synthetic or natural oxide or iron base.

The natural oxides are natural earth pigments, washed and decanted. These are dull earth pigments, in contrast with the azo pigments. They allow darker mixes and a good range of browns and greys. They are semi-opaque pigments. Their drying times are quite short and have an improved grain size. In the Charbonnel colour range, only Raw Sepia has a natural iron oxide base.

The synthetic oxides possess the characteristics of the natural oxides without their defects. They are more lively, less grainy and dry more rapidly. They are also semi-opaque.

BLACKS. These are composed of ivory black and carbon black. Ivory black has a bluish tint, a rather long drying time and is opaque. Carbon black is more powerful with a shorter drying time than ivory black. The ratio of the two types of black varies depending on the type of black concerned (see classification table for the blacks). The blacks differ not only in shade but also in viscosity.

They contain 200 poise linseed oil (very high viscosity), 30 poise linseed oil (medium viscosity) and colourless linseed oil a low viscosity). The proportion of the three oils gives a particular viscosity to each black (see classification table for the blacks). The proportion between pigment content and oil also plays an important role in the viscosity and depth of the black.

WHITES. These are composed of zinc white' and titanium white. Titanium white is very powerful with a high covering power. Zinc white is less covering, a little less powerful and tends to slightly change on steel covered plates. The whites have the same viscosity as the Charbonnel colours.

METALLIC COLOURS. Gold has a natural bronze base pigment and silver an aluminium base pigment. The pigment particle size of the shades is larger and the paste thicker than the others because they cannot be ground. Grinding would actually crush the pigment, which would lose all its metallic characteristics.