Editing Sizing (section)

== Surface sizing ==
Surface sizing solutions consist of mainly modified [[starch]]es and sometimes other hydrocolloids, such as [[gelatine]], or surface sizing agents such as [[acrylate polymer|acrylic co-polymers]]. Surface sizing agents are [[Amphiphile|amphiphilic]] molecules, having both [[Hydrophile|hydrophilic]] (water-loving) and [[Hydrophobe|hydrophobic]] (water-repelling) ends. The sizing agent adheres to substrate fibers and forms a film, with the hydrophilic tail facing the fiber and the hydrophobic tail facing outwards, resulting in a smooth finish that tends to be water-repellent. Sizing improves the surface strength, printability, and water resistance of the paper or material to which it is applied. In the sizing solution, [[optical brightener|optical brightening agents (OBA)]] may also be added to improve the opacity and whiteness of the paper or material surface.