The primary binders traditionally used in tempera paint are egg yolk, milk (in the form of casein), and various plant gums. These natural substances are mixed with dry powdered pigments to create a durable, fast-drying paint.
Understanding Tempera Paint
Tempera is an ancient painting medium, popular before the advent of oil paint. It is known for its luminous colors, fine detail capabilities, and matte finish. The process involves hand-grinding dry powdered pigments and carefully mixing them with a binding agent. This binder acts as the adhesive, holding the pigment particles together and allowing them to adhere to the painting surface.
Key Tempera Binders
While "tempera" often refers to egg tempera, the term encompasses several traditional binding agents. Each binder imparts distinct characteristics to the paint.
1. Egg Yolk (Egg Tempera)
Egg yolk is arguably the most famous and widely recognized binder for tempera paint. This form is specifically known as egg tempera.
- Composition: The yolk of a chicken egg contains a natural emulsion of water, fats, and proteins, which serves as an excellent binder.
- Characteristics:
- Dries quickly to a matte or satin finish.
- Creates extremely durable and stable paint films.
- Allows for very fine lines and precise detail, often applied in thin, transparent layers or cross-hatching.
- Does not yellow over time, unlike some oil-based mediums.
- Preparation: Artists typically separate the yolk from the white and pierce the membrane to extract the pure yolk, which is then diluted with water, sometimes with a touch of vinegar or wine as a preservative.
2. Casein (Milk Tempera)
Casein, derived from milk protein, is another significant binder used in tempera, often referred to as casein tempera or milk paint.
- Composition: Casein is the principal protein found in milk. It is typically prepared by precipitating the casein from skim milk using an acid (like vinegar) and then dissolving it in an alkali (such as ammonia or borax) to create a workable glue.
- Characteristics:
- Dries to a highly opaque, matte finish.
- Known for its strong adhesive qualities once dry, becoming quite water-resistant.
- Can be used for murals and decorative painting due to its durability.
- Often produces a slightly more textural paint than egg tempera.
3. Plant Gums (Gum Tempera)
A variety of plant gums can also serve as binders for tempera paint, collectively known as gum tempera.
- Composition: These are natural polysaccharides extracted from plants. Common examples include gum arabic (from acacia trees) and tragacanth gum.
- Characteristics:
- Typically dries to a more transparent or translucent finish compared to egg or casein.
- Can produce a slightly glossy sheen, depending on the gum and dilution.
- Often used for fine art applications, similar to watercolors or gouache, which also frequently use gum arabic.
- Re-solubilizes with water even after drying, making it less permanent than egg or casein tempera unless specific additives are used.
Comparison of Tempera Binders
| Binder Type | Key Characteristics | Common Uses | Finish When Dry |
|---|---|---|---|
| Egg Yolk | Fast-drying, durable, precise detail, stable colors | Panel painting, illuminated manuscripts, fine art | Matte to Satin |
| Casein | Opaque, strong adhesion, water-resistant once dry | Murals, decorative arts, historical wall paintings | Opaque Matte |
| Plant Gums | Transparent/translucent, re-soluble, good for washes | Illustrative work, historical manuscripts, flexible film | Transparent/Glossy |
The Legacy of Tempera
The choice of binder significantly influences the paint's working properties and final appearance. While modern paints often utilize synthetic polymers, traditional tempera mediums, particularly egg tempera, continue to be valued by artists for their unique qualities and historical significance. The meticulous process of grinding pigments with these natural binders connects contemporary artists to centuries of artistic tradition. For further exploration of tempera painting techniques, resources like Wikipedia's Tempera entry offer extensive historical and practical information.
