Optical Brightening Agents (OBA) or Fluorescent Whitening Agents (FWA) is added to many substrates to reduce yellowing, improve whiteness and enhance the brightness of the product. Optical whiteners function by absorbing ultraviolet radiation and re-emitting blue light. The emitted blue light will reduce the yellow color of the substrate and impart a pleasing whiter-than-white appearance. Optical brighteners give more intensity to some colors as well.
 
Different Types of Optical Brightening Agent find suitable application on different substrates like Cellulose, Nylon, Silk, Wool, Paper, Detergents, Soaps, Plastics, Printing Inks, Coatings and Polymers.

There are 3 different types of OBA / FWA based on the sulfonic group.

Disulfonic / Divalent
It constitutes of two sulfonic acid groups and is good for hydrophobic fiber (nylon, silk & wool) application in Acidic pH.

Tetrasulfonic / Tetravalent
It constitutes of four sulfonic groups and is having good solubility and is ideal for cellulosic fiber and paper application at neutral or alkaline pH.

Hexasulfonic / Hexavalent
It constitutes of six sulfonic groups and has excellent solubility for surface coating application like photographic paper etc