Analysis of Causes of Discoloration of Overalls

It's quite common for dark-colored clothing to experience fading over time. When fabrics are dyed, they go through multiple washes and are often exposed to sunlight, which can lead to photodegradation and aging of the dyes. This causes the colors to gradually lose their vibrancy, and the process is usually slow and complex.

When sunlight hits dyed clothes, the energy from the light activates the dye molecules. These active molecules can then react with substances in the environment. Oxygen in the air is one of the main participants in this reaction, and moisture can significantly speed it up. Depending on the type of fabric and the dye used, the result may be oxidation or reduction, both of which contribute to color loss.

For example, cotton fabrics dyed with azo dyes tend to fade due to oxidation when exposed to sunlight. However, protein-based fibers like silk or wool treated with the same type of dyes may fade through a reduction process instead. This difference highlights how the interaction between the fabric and the dye plays a key role in color stability.

The structure of the dye molecule itself also affects how well it resists fading. Dyes with unstable structures are more prone to discoloration. Molecules that contain reactive hydrogen atoms can accelerate oxidation, making them less lightfast. On the other hand, certain functional groups—such as amino (-NH₂), hydroxyl (-OH), carboxyl (-COOH), sulfonic (-SO₃H), or nitro (-NO₂) groups—can enhance lightfastness by stabilizing the dye or reducing its reactivity under UV exposure.

Understanding these factors helps in choosing more durable dyes and properly caring for colored garments to maintain their appearance over time.