How Do Fabric Brighteners Work?

Fabric brighteners, found in most detergents, don't clean clothes but enhance their appearance by making them glow. They work by absorbing ultraviolet light and emitting blue light, which masks yellowing and small stains. This effect is due to optical brighteners, a type of fluorescent chemical. While they make clothes look cleaner, they don't prevent fading caused by washing or sunlight. Historically, blue dye was used for similar effects. However, optical brighteners can be problematic in military settings as they are visible through night-vision goggles, leading to their ban in such contexts.

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