Question

Colourless fluorescent dyes which turn pale fabrics white making them look brighter are called ______.

Options

• Bleach

• Blue

• Stiffening agents

• Optical brighteners

Answer 1

Colourless fluorescent dyes, which turn pale fabrics white, making them look brighter, are called optical brighteners.

Explanation:

Optical brighteners are colourless fluorescent dyes that absorb invisible ultraviolet light and reflect it back as visible blue-white light. This chemical reflection counteracts any yellowish tint on pale fabrics, making them appear significantly whiter and brighter to the human eye. Unlike chemical bleaches or traditional laundry blues, they do not remove dirt or add colour pigments; instead, they work entirely by improving light reflection.