lichtbeständig

Lichtbeständig, or lightfast, describes the resistance of a material’s color or appearance to fading or change when exposed to light, especially ultraviolet radiation. It is a critical property for pigments and dyes, coatings and paints, plastics, textiles, and printed materials that are used outdoors or in bright environments.

Measurement and assessment are based on standardized test conditions that expose samples to light for a defined period and measure color change, typically as ΔE on a color space or as a qualitative rating. Common test methods use artificial light sources such as xenon-arc lamps or fluorescent lamps, sometimes with cycling to simulate day-night or weathering conditions. Results are reported as a rating or category linked to expected performance under specified conditions. Accelerated tests aim to predict long-term outdoor performance but may not capture all real-world factors.

Materials and trends: Inorganic pigments (for example, titanium white, ultramarine, carbon black) generally exhibit high lightfastness, while many organic pigments and dyes are more prone to fading unless protected. The binding medium, coating system, and the presence of UV absorbers or stabilizers influence results. Outdoor exposure, heat, humidity, and oxygen can accelerate degradation.

Context: Lichtbeständigkeit is a key specification in product standards for outdoor paint and coatings, automotive finishes, solar protection materials, textiles, and packaging. It is one factor among others such as heat and UV stability, chemical resistance, and overall weather resistance.