CREATIVE TECHNIQUES – What Are Pigments?
Since my work displays the use of earth colors I believe it is a good idea to look into these pigments. First, what are pigments? Pigments are solid materials in the shape of small separate particles. The majority of pigments are now created from complex carbon chemistry. In the past pigments were derived from natural substances. Above: Natural ultramarine pigment in powdered form — wikipedia.
Before a pigment can be applied unto a substrate, it must be dispersed in a binding medium. In acrylics, the binder is known as “polymer medium”, which is composed of 50% water and 50% acrylic polymer solids. Add surfactants, additives, and preservatives and you have your “acrylic binder”. Add pigment and you have paint!
The size and shape of pigment particles affect the appearance of the paint – large particles tend to produce a matte, grainy texture and particle size can affect paint stability. Smaller particles allow for less settling of the pigment. Coarser particles and their propensity to settle faster are what make inorganic pigments (earth colors) more difficult to stabilize in the more fluid formulations.
There are two types of pigments that paints are made with: Inorganic and Organic.
Inorganic pigments are derived from natural mineral or ores, commonly referred to as earth colors: Siennas, Umbers, Oxides, Cadmiums, Cobalts and Titaniums. These pigments are like minute rocks: dense, heavy, matte and opaque (light does not penetrate through these materials). The paint that is formulated will have more matte opaque pigment in ratio to the glossy binder. Once dry, inorganics have a matte surface.
Organic pigments have been synthetically manufactured in labs within the last fifty years. Organic pigments are formed from complex carbon chemistry and have chemical sounding names: Quinacridone, Naphthamide, Phthalo, Hansa and Anthraquinone. Generally, these pigments are translucent in nature and when viewed through a microscope often look like pieces of stained glass. Light does transmit through these pigments.
When inorganic pigments (mineral) are mixed together, they produce a “muddy” or low chroma mixture. Mix organic pigments together and the colors retain their clarity and brightness, and have a higher chroma. Chroma is another word for intensity or saturation.
There are 3 types of inorganic pigment: earth, mineral and synthetic. Earth pigments are the natural weathering of various manganese ores and feldspartic rock (which contains aluminum and silicon). (Artist’s Handbook by Ray Smith, p. 13) Ochres and umbers are part of these earth pigments. Mineral pigments occur naturally as minerals. Cinnabar (vermilion), Lapiz Lazuli (ultramarine), white minerals which can be used for grounds and for gesso. The last category is the synthetic inorganic pigments which are manufactured. These include Titanium and Zinc White. In the yellows and reds we have Naples Yellow and Cadmiums. The popular Phtalo Blue (which replaced Prussian Blue), Cobalt and Cerulean Blue form the synthetic inorganic blue group. Cobalt Green and Viridian, the green group.Back