Kiiltävyys

Kiiltävyys, meaning gloss or glossiness in English, is a surface optical property describing how strongly a surface reflects light in a specular direction. It is distinct from color, brightness, and texture: a surface can have high kiiltävyys but a dull color or low color saturation; conversely, a matte surface can reflect similar amounts of light diffusely with low kiiltävyys. Kiiltävyys is primarily determined by surface smoothness on the scale of the light wavelength and by the quality of any coatings. Polished metals, smooth plastics, glossy paints, and wet surfaces typically exhibit high kiiltävyys; rough textures scatter light and have low kiiltävyys.

Measurement: Kiiltävyys is quantified with a gloss meter in defined geometries (commonly 20°, 60°, or 85°) and reported as gloss units (GU) or percent reflectance. Higher GU indicates stronger specular reflection. The choice of geometry depends on the expected surface finish and industry standards. Surface preparation, contamination, and viewing angle can affect results.

Factors: Process parameters (polishing, coating thickness, curing), surface energy, and micro-roughness influence kiiltävyys. Aging and environmental exposure can reduce kiiltävyys through wear, oxidation, or fouling.

Applications: In manufacturing and quality control, kiiltävyys is used to specify product appearance—paints, coatings, plastics, paper, and cosmetics. It interacts with other optical properties such as haze, clarity, and color.

See also: Gloss (optics), Specular reflection, Surface roughness, Gloss meter.