Understanding Color Theory: Pigments, Light & Perception
Color Theory: Light, Pigments, and Perception
What is Color?
When referring to a colored substance, color is the light composed of base colors (red, green, blue, violet) that is captured by the eye. Color and color pigment are sensations produced when the eye is stimulated by different light waves.
Color Perception
Color perception begins when light passes through the eye’s lens and reaches photoreceptor cells called cones (6 million) and rods (120 million). Rods and cones collect part of the light spectrum and, through the photoelectric effect, transform it into electrical impulses sent to the brain via the optic nerves, creating a sense of color.
Cones are classified as:
- Short wave (blue)
- Medium wave (green)
- Long wave (red)
When the cone system is not functioning correctly, rods can cause irregularities such as color blindness.
Light Source and Color
- Light color: Produced by a light source.
- Matter color: Produced by light reflected from a colored body.
Additive Color Mixing (Light)
Mixing colored lights is called additive synthesis because the results are obtained by adding light to light. The sum of the primary light colors (blue-violet, red-orange, and green) results in white or colorless light (the most light).
In additive synthesis, pure, fully saturated colors do not contain any white light. Examples include:
- Fully saturated red
- Orange
- Yellow
- Green
- Blue
- Indigo
- Violet
Additive synthesis is achieved by projecting pure lights onto a white screen in a completely dark room.
Subtractive Color Mixing (Pigments)
Light awakens color by interacting with matter. Depending on its molecular structure, matter reflects, absorbs, or transmits light.
- Transmitted color: The color that passes through transparent bodies.
- Reflected color: The color reflected by opaque materials after absorbing some light rays.
Mixing pigment colors is called subtractive mixing. Each pigment has a selective power and absorbs certain wavelengths.
Subtractive Primary Colors
These colors cannot be obtained by combining other colors and can be mixed to create many color ranges.
Example:
- Yellow absorbs blue (short), reflects green (medium), and red (long).
- Cyan absorbs red, reflects green and blue (short and medium).
Complementary Colors
- Yellow – Blue-violet
- Magenta – Green
- Cyan – Red
Color Properties
- Hue: The essential quality that distinguishes one color from another.
- Saturation: The vividness or purity of a color.
- Brightness: The visual sensation of the presence of light.
Note: Saturation decreases when white is added, and brightness decreases when black is added.
Art Materials
Support
The structure or surface on which art materials are applied (e.g., canvas, paper).
Pigment
A solid color material in the form of small, separate particles.
Types of Pigments:
- Inorganic Natural: Extracted from nature without human manipulation (e.g., iron oxide, ochre clay).
- Mineral: Extracted directly from minerals (e.g., cinnabar).
- Organic Animal: Derived from animals (e.g., carmine, sepia, Indian yellow).
- Organic Plant: Derived from plants (e.g., charcoal, black smoke, vegetable tints).
- Artificial: Created in laboratories since the 1930s.
Binder
A substance that holds pigment particles together and allows them to adhere to the support (e.g., oil, acrylic).
Filler
Materials, usually limestone, used in the manufacture of drawing and painting media. They serve as fillers and do not alter the color or composition (e.g., chalk).
Acrylic Paint
A recent invention, acrylic paint is a water-based suspension of pigments with polymerized synthetic resin particles. Upon evaporation, it forms a chemically inert, flexible, light, solid, and unchanging film.
Acrylic paint is available in various forms (tubes, plastic bottles, metal cans) and offers several advantages:
- Easier to use than oil paint.
- More possibilities for shades (can dry two shades darker).
- Dries very fast.
- Combines opacity and transparency effects.
- Offers a variety of consistencies, viscosities, and textures.
Acrylic paint allows for various techniques, including fast and direct application, transparent and opaque washes, layering, scraping, pressing, pulverizing, and mixing with putty.
Canvas
The most commonly used support for painting, typically made of cotton, linen, or a blend of both, stretched on a frame.
Brushes
Made up of three parts: handle, ferrule, and hair. Finer hair provides greater ability to hold pigment loads. High-quality, long-lasting brushes are often made with mahogany hair. Less elastic options include squirrel, ox, or synthetic hair. Brushes come in various shapes and sizes:
- Round: Round tip, suitable for watercolor.
- Square: Short and square tip.
- Flat: Similar to square but longer.
- Cat’s Tongue: Curved inward ends.
- Fan: Used for blending wet paint areas.