whiteners

Whiteners are substances that impart whiteness or brightness to materials by reflecting light, masking yellowing, or bleaching color. They are used in textiles, foods, cosmetics, dentistry, and industrial materials and can function as bleaching agents, pigments, or optical brighteners.

In laundry and textiles, chlorine-based bleaches such as sodium hypochlorite remove color by oxidation, while peroxide-based bleaches (hydrogen peroxide, sodium percarbonate, or sodium perborate) rely on active oxygen to break down stains. Optical brighteners or fluorescent whitening agents, often derived from stilbene or related structures, do not remove stains but absorb ultraviolet light and re-emit blue light, helping fabrics appear whiter.

In foods and consumer products, whiteners include white pigments such as titanium dioxide (though regulatory status varies by region) and minerals like calcium carbonate used to brighten colors or stabilize texture. Titanium dioxide has faced regulatory scrutiny in several jurisdictions. Other whitening fillers may be used in pharmaceuticals and cosmetics.

Tooth whiteners are peroxide-based agents used in dentistry and in over-the-counter products; hydrogen peroxide or carbamide peroxide break down to reactive oxygen species that bleach enamel. Efficacy and safety depend on concentration and application duration; possible side effects include tooth sensitivity and gum irritation.

Industrial applications include whitening of paper, plastics, and inks, often using optical brighteners to improve perceived whiteness under UV light. Safety and environmental considerations include handling hazards from bleach reagents, potential release of reactive oxygen species, and regulatory restrictions on certain whitening pigments.