Sunlight fastness

Sunlight fastness refers to a material's ability to withstand exposure to sunlight without fading, discoloring, or degrading over time. It measures how well dyes, paints, or fabrics resist UV rays, which can break down colors and weaken materials. A high sunlight fastness indicates the item will maintain its appearance longer when exposed outdoors, while low fastness means it may fade quickly. This property is important for outdoor use, ensuring that colors stay vibrant and material integrity is preserved despite prolonged sunlight exposure.