A Fluorescent Whitening Agent (FWA), also known as an optical brightener, is a chemical compound used to enhance the appearance of colors and whiteness in materials. It works by absorbing ultraviolet light and re-emitting it as visible blue light, giving treated surfaces a brighter and cleaner look.

These agents are widely used in industries such as textiles, plastics, paper, and detergents. In textiles, for example, FWAs are applied to fabrics to neutralize yellowish tones and enhance visual brightness without adding dye. This is particularly useful for white cotton or synthetic fibers.

The optical effect created by FWAs is not a permanent change in material color, but rather a light-based adjustment in perception. This makes them a cost-effective solution for improving aesthetic appeal without altering the structural properties of the material.

Fluorescent whitening agents vary in chemical composition based on the application. For instance, stilbene derivatives are common in detergents, while triazine-stilbene compounds are often used in synthetic resins. The selection depends on compatibility with the substrate and stability under processing conditions like heat or light exposure.

In summary, fluorescent whitening agents play an important role in visual enhancement across multiple industries, offering a practical method for improving material brightness through a subtle optical effect.