The color fastness of textiles refers to the ability of a fabric to retain its color when exposed to various external factors. Several factors can affect the color fastness of textiles, including:

1. Light: Exposure to sunlight or artificial light can cause fading or discoloration of textiles. Ultraviolet (UV) radiation is particularly damaging to colors.

2. Washing: Repeated washing, especially with harsh detergents and at high temperatures, can lead to color fading or bleeding. Aggressive washing techniques, such as rubbing or scrubbing, can also affect color fastness.

3. Bleaching agents: The use of bleaching agents, such as chlorine bleach, can significantly impact color fastness. Bleach can cause color loss or change in textiles.

4. Perspiration: Contact with sweat can affect color fastness, particularly in garments that come into direct contact with the skin. The pH and composition of perspiration can vary among individuals and affect color stability.

5. Environmental factors: Exposure to pollutants, chemicals, and atmospheric gases can contribute to color fading or degradation. This includes exposure to gases like ozone and sulfur dioxide.

6. Friction and abrasion: Repeated rubbing or friction, such as during wearing or washing, can affect color fastness. Areas of high friction, like elbows or cuffs, are more prone to color loss or fading.

7. Sublimation: Some dyes may undergo sublimation, where they transition directly from a solid to a gas state without passing through the liquid phase. This can cause color loss or transfer to other surfaces.

8. pH levels: Extreme pH levels, either highly acidic or highly alkaline, can affect the stability of dyes and pigments used in textiles, resulting in color changes or fading.

9. Heat: Exposure to high temperatures, such as during ironing or hot water washing, can impact color fastness. Heat can cause dyes to break down or migrate from one area to another.

To ensure optimal color fastness, it is recommended to follow care instructions provided by the manufacturer, use gentle washing techniques, avoid harsh chemicals, and protect textiles from excessive exposure to sunlight or other damaging conditions.