The answer distinguishes between what we can manufacture as a pigment and what is possible through advanced engineering. Black is the perception that results from the complete absorption of visible light, meaning no light is reflected back to the eye. A theoretical perfect black body would absorb 100% of all incident radiation, but no conventional material achieves this absolute darkness. Real-world materials, including the blackest pigments, still reflect a small fraction of light, and the search for “super-black” materials is an attempt to close that gap.
Understanding the Concept of Black
Black is not a color in the traditional sense, but rather the absence of visible light reaching the observer’s eye. When white light strikes an object, the surface determines which wavelengths are absorbed and which are reflected. An object appears black because it absorbs nearly all wavelengths of visible light and reflects almost none of them.
Physicists use the concept of a perfect black body, which is an idealized object that absorbs 100% of all electromagnetic radiation falling upon it. This theoretical standard serves as the benchmark for darkness, with zero reflection and zero transmission of light. Manufactured black materials are only approximations of this perfect absorber, reflecting a small percentage of light.
Carbon Black: A Standard for Pigment Darkness
Carbon Black (CB) is a material composed of fine particles of amorphous carbon, produced by the incomplete combustion or thermal decomposition of hydrocarbon products. Its structure, characterized by small primary particles and a high surface area, allows it to absorb light across the entire visible spectrum efficiently. This high intrinsic absorptivity makes Carbon Black the standard for deep black coloration in industrial applications.
As a pigment, Carbon Black is widely used in tires, plastics, printing inks, and paints, providing a durable and opaque black color. High-quality pigment-based coatings absorb over 98% of incident visible light, reflecting roughly 1% to 2%. This establishes Carbon Black as the practical benchmark for conventional black coatings. The small particle size prevents significant light scattering, which would reduce the perceived blackness.
Quantifying Darkness Through Reflectance
Darkness is quantified using objective scientific measurements, primarily through reflectance, to move beyond subjective visual comparisons. Reflectance is the percentage of light a surface bounces back; a lower percentage indicates a darker material. This measurement is performed using a spectrophotometer, which measures the light reflected at various wavelengths.
The industry standard for measuring lightness and darkness is the L value, part of the CIELAB color space. The L axis represents the lightness scale, ranging from a theoretical black at L = 0 to a theoretical white at L = 100. A standard, high-quality Carbon Black paint achieves an L value of 1.0 to 3.0, corresponding to a very low reflectance percentage. Efforts to create materials darker than Carbon Black focus on pushing this L value as close to zero as possible.
Ultra-Black Materials Engineered Beyond Pigments
While Carbon Black is an exceptionally dark pigment, engineered materials surpass its light absorption capabilities. These ultra-black materials achieve superior performance through their microscopic structure, not just chemical composition. They utilize a physical mechanism to trap light, rather than relying solely on pigment absorption.
The most notable examples are coatings made from vertically aligned carbon nanotube (CNT) arrays, such as Vantablack. These materials are composed of millions of tiny, densely packed tubes standing upright like a microscopic forest. When light enters the gaps between the nanotubes, it becomes trapped, undergoes multiple internal reflections, and is nearly all absorbed. The light is unable to escape the structure.
This geometric light-trapping mechanism allows ultra-black materials to reach absorption rates of 99.9% or higher across the visible spectrum. Some CNT-based coatings have demonstrated an L value near 0.1, making them visually indistinguishable from a void. This makes them significantly darker than Carbon Black, which is limited by the scattering and reflection inherent to its particle-based composition.