Black is arguably the most iconic color. It’s sleek, dramatic, and ubiquitous in art and design. But what makes black pigment so dark and how does it absorb light so completely?
The science of black
Black pigments get their color from carbon. Carbon atoms bond tightly together to form hexagonal sheets. When stacked together, these sheets absorb virtually all visible light wavelengths.
Light wavelengths strike the surface of the carbon pigment but cannot penetrate past the first few layers of carbon sheets. With nowhere to go, the light is simply absorbed rather than reflected back to our eyes, creating the appearance of black.
Properties of black pigments
The most common black pigments include:
- Carbon black – Soot or charcoal powder
- Bone black – Charred animal bones
- Iron oxide black – Black iron oxide particles
- Manganese black – Manganese oxide
Carbon black has been used since prehistoric times. It provides the deepest black but is also the least lightfast. Bone black was very commonly used in Renaissance oil painting. Modern synthetic iron oxide blacks are very lightfast and mixable.
| Pigment | Lightfastness | Staining |
|---|---|---|
| Carbon black | Poor | High |
| Bone black | Moderate | Slight |
| Iron oxide black | Excellent | Low |
Carbon black has a high tinting strength, meaning you need very little pigment to produce a deep black color. However, it also has a high staining capacity and can be difficult to wash out of brushes and skin.
Making black pigments
Prehistoric carbon black pigment was produced by burning organic materials like bone, plants, and wood. The resulting soot was collected and mixed with animal fat to produce a paint or ink.
Later methods boiled the soot in wine or vinegar to improve the pigment quality. Vinegar helped aggregate the carbon particles into larger clusters that absorbed more light and produced a deeper black.
Bone black was made by charring animal bones in closed vessels. The dry distillation process vaporized the organic components and left a pigment composed mostly of carbon with traces of calcium phosphate.
Modern black pigments are synthetically engineered for improved lightfastness. Furnace carbon black is created by partial combustion of oil feedstocks. Different grades are used in paints, inks, plastics, and rubber.
Synthetic iron oxide blacks are made by oxidizing iron salts. They come in two main forms:
- PBk11 – Iron(II,III) oxide
- PBk9 – Iron(II) manganese oxide
Manganese black is produced by heating manganese dioxide ore in a kiln. This creates an extremely lightfast pigment due to its mineral composition.
Artistic uses
Throughout history, black has been one of the most widely used colors in art. Some key examples include:
- Prehistoric cave paintings used charcoal and soot to create black outlines and silhouettes.
- Ancient Egyptian art used carbon black and bone black along with ochre to create bold outlines and contrast.
- Renaissance oil painters glazed over underlayers of bone black to produce deep, transparent darks.
- Impressionist painters like Manet used modern tube paints with carbon black to create dramatic tonal effects.
Many modern and contemporary artists have continued to explore the symbolism and visual impact of the color black:
| Artist | Use of black |
|---|---|
| Kasimir Malevich | His iconic Black Square (1915) became a symbol of Suprematism. |
| Mark Rothko | Layered black over other colors to create meditative effects. |
| Frank Stella | Used thick black lines in his geometric minimalist paintings. |
| Anish Kapoor | Worked with a patented “vantablack” said to be the blackest black pigment. |
As a cultural symbol, the color black communicates power, mystery, and solemnity. As a pigment, carbon-based black offers artists a versatile dark with strong visual impact.
Black and light
What makes black so black? In short, it’s because black absorbs all visible light wavelengths striking its surface.
White objects appear white because their surfaces reflect all visible light equally. Black surfaces work in the opposite manner. When light hits a black pigment, all the wavelengths are absorbed rather than reflected back to our eyes.
This total absorption of light gives black its distinctive heavy, dark appearance. It’s as far from white on the color and light spectrum as possible.
Black in nature
While black pigments absorb light, black in the natural world is often created by microscopic and nano-scale structures that prevent light reflection in the first place.
Some examples of black in nature include:
- Raven feathers – Overlap of microscopic barbs traps light between barbs
- Butterfly wings – Minute scales scattered light through diffraction
- Beetle shells – Exoskeleton with nano-sized pits prevent light reflection
Rather than pigments, these microscopic light-trapping structures create black through optical effects at the surface interface of the material.
Black materials
Manmade materials can also leverage surface structures to absorb or trap light. Some examples include:
- Black 3D printed materials – Microscopic geometric shapes prevent light reflection
- Vantablack – Forest of vertical nanotubes absorbs over 99% of light
- Carbon nanotubes – React with light to create black coatings
While black pigments use hexadecimal carbon sheets to absorb light, black engineered materials rely on microscopic surface structures to prevent light reflection and scattering.
Black holes
The blackest natural black comes from black holes. Their immense gravitational pull traps all light and prevents any from escaping.
Within the event horizon of a black hole, light cannot reflect or refract away from the surface. The inside of a black hole can be thought of as the total absorption of light taken to its theoretical limit.
Interestingly, while black holes appear perfectly black from the outside, current physics predicts their behavior and contents are far more complex.
Conclusion
Whether occurring in the nano-structures of feathers, the carbon layers of pigments, or the light-bending forces of black holes, black arises from the total absorption or exclusion of visible light.
As an artistic symbol, black communicates solemnity and mystery. As a scientific phenomenon, black reveals the interplay between light, matter, and perception.
From many perspectives, black represents the absence of light. Yet as a color, black has a commanding presence all its own.