What is color fastness?
Aug 11, 2026
Color fastness is a measure of a material's (usually textile, fabric, or leather) resistance to fading or bleeding of its color when exposed to various conditions. It tells you how well a dyed or printed material retains its original color appearance under stress.
Key types of color fastness include:
Wash fastness - resistance to color loss and bleeding when laundered.
Light fastness - resistance to fading from sunlight or artificial light exposure.
Rubbing/crocking fastness - resistance to color transfer when rubbed, either dry or wet.
Perspiration fastness - resistance to color change from sweat, which is important for activewear and garments.
Water fastness - resistance to color run when exposed to water or rain.
Heat/pressing fastness - resistance to color change from ironing or hot pressing.
Color fastness is important because poor fastness means a garment fades quickly, stains other clothes in the wash, or discolors during wear and care. It's a key quality testing standard in the textile industry (e.g., AATCC and ISO test methods) and is often graded on a scale, typically 1 (very poor) to 5 (excellent) for most tests, or using a blue wool scale for light fastness.
In short, good color fastness means the color stays put under everyday conditions; poor fastness means your red socks will eventually dye everything in the laundry pink.
