See acid, weak or base, weak

A chemical that helps water penetrate a material or form a film over its surface; usually a surfactant. Wetting agents are often used in dyeing to help the dye solution penetrate to the individual fibers (they don’t usually help the dye penetrate from the surface of the fiber to the interior of the fiber). They can help in some fiber arts dyeing processes, but too much in a dye solution used for direct application may make the dye spread more than is wanted.

Color Index Reducing Agent 6, used for discharge. This discharge agent works best in mildly acid conditions, so it is preferred, over sodium formaldehyde sulfoxylate, for work on wool. It is also often used in discharge screen printing of garments. - Rev 2.0.0a