Glossiness

Glossiness describes how much a surface reflects light in a specular, mirror-like manner. A highly glossy surface produces sharp, bright reflections, whereas a matte surface scatters light diffusely and appears dull. Glossiness is influenced by surface smoothness and finish.

The appearance depends on micro-scale roughness, coating thickness, and the material's refractive index. Surface texture, contaminants, and color can alter perceived gloss. Gloss also varies with the angle of illumination and observation; some surfaces look glossier when lit from certain directions.

Measurement uses gloss meters and standardized geometries. Gloss is reported in gloss units (GU) and is defined in standards such as ISO 2813 for 20°, 60°, and 85° measurement angles. Higher GU denotes higher gloss; some materials are better characterized at multiple angles because gloss changes with angle.

In industry, gloss is critical for paints, varnishes, plastics, and metals. Automotive finishes, furniture coatings, and ceramic glazes are specified by gloss levels to meet aesthetic and functional requirements. Gloss also interacts with durability, as coatings with high gloss can show scratches more readily.

In computer graphics, glossiness often represents surface sharpness in BRDF-based rendering. In many workflows, a glossy surface is modeled with a microfacet distribution; roughness is the inverse of glossiness. In physically based rendering (PBR), roughness or gloss maps control specular highlights and reflections.

Glossiness and gloss are related but not identical to specular reflectivity; they describe the quality of reflection rather than its amount. The term is used across disciplines, from industrial coatings to digital rendering.