Paints

  

Paints are the combination of coloring material and finely ground pigment, mixed to a smooth consistency with a binder. The pigments themselves can be broadly classified as either organic (derived from living organisms) or inorganic (minerals).

Pigments
Inorganic pigments are of mineral origin, some of which include raw umber, ochre, burnt umber and burnt sienna. Artificially prepared mineral colors include cadmium yellow, zinc oxide, etc. Organic pigments are of animal, vegetable or synthetic origin and include indigo, madder, Indian yellow, etc. Synthetic organic pigments such as cerulean blue, cobalt green and cobalt yellow are characterized by great brilliance and intensity and should not be thought of as inferior to their natural counterparts.

Because of the many variable conditions both in nature and in the manufacturing process, many qualities of pigments exist. Most paints are sold in artist and student grade. Artist quality paints contain the best pigments. Student colors generally contain the cheaper pigments, and are coarser in texture. Hue is another way of classifying a paint. Often substitute pigments are used in student grade colors to reduce cost and are hence labeled “hue.” Sometimes the original colors no longer exist, such as with Indian yellow hue, or original pigments are found to be poisonous and are substituted as in the case of Naples yellow hue.

Binders
Each type of paint has a different binder that mixes with a pigment to create a smooth consistency. For example, linseed oil is the binder used for oil paint, gum arabic binder for watercolors and acrylic emulsion is the binder for acrylics.

Three Common Paints
Watercolor is a transparent medium made from refined water-soluble pigments, available in both pan and tube form. It is highly suitable for subtle renderings on paper and board. Oil color is mixed with linseed oil and dries very slowly. It is usually used on primed slightly absorbent surfaces such as canvas, board and masonite. Acrylic paint represents a technological advance in the formulation of artist’s color. It is a quick drying synthetic plastic emulsion, which behaves both like watercolor and oil paints as it is capable of thinned application for wash effects and can be used for thick impasto techniques.

The Newest Paint Develoments
New paints and paint vehicles have been emerging recently in the art world, somewhat unlike the traditional products artists have been used to. Some of these follow.

  • Interference Paints
    Surfaces painted with these colors look different depending on the angle at which they are viewed and the angle of the light striking the surface. These paints contain tiny flakes of mica, coated with titanium dioxide, which enable the paint to refract its complement color. They can be used alone, mixed with
    non-interference acrylic paints, or layered translucently over an already painted area. Interference paints can also be used for fabric and airbrush techniques.
  • Iridescent Paints
    These paints are like interference paints but are opaque. They do not have as large of a color refraction but produce a shimmery metallic effect.
  • Metallic Paints
    These paints actually include metal particles that simulate the luster of such metals as gold, silver and bronze.
  • Fluorescent Paints
    These paints appear to glow as they absorb light of one wavelength and re-emit it at a different wavelength. These paints are not lightfast and should not be used for permanent painting.

 

 Helpful Hints

Understanding Lightfastness Ratings
The lightfastness of paints is the ability of the paint to resist color change and fading when exposed to light. The American Society for Testing and Materials (ASTM) has developed standards that manufacturers have adopted for testing and labeling their paints.

Lightfastness Category I (LFI): excellent lightfastness under all normal lighting conditions.

Lightfastness Category II (LFII): very good lightfastness, satisfactory for all applications except those requiring prolonged exposure to ultraviolet light–for example, outdoor murals.

The Paints You May Not Know About
Alkyd paints are used in the same manner as oil colors but have a quicker drying time and the reputation of producing more intense colors than oils. They can be mixed with oil paints and are soluble in turpentine. Casein paints have a binder that’s a derivative of milk curd. Because they’re water-based, they can be thinned with water to different consistencies. They’re strongly adhesive and dry quickly to an even matte finish. Gouache paints are smooth, opaque watercolors. They’re good for fine lines and can be built up in layers. They also dry quickly to a uniform matte finish. Egg-tempera paints are based on an egg-oil emulsion. Inexpensive school version tempera paints are different than egg-tempera paints which are high grade artist’s paints. They can be used as an underpainting for oils or as a medium in itself. They are usually applied in thin layers (thick ones may flake) and dry very quickly.