The use of surfactants has been limited over the years due to caustic soda’s high concentration (50% NaOH). Surfactants are known as “surface active agents.” They have the ability to reduce surface tension which will allow better rinsing. For this reason, they are also known as “wetting agents.”

Wetting agents are more generally known as synthetic detergents of which there are four types: anionic, nonionic, cationic, and amphoteric. The anionic types are more commonly used in detergent formulations, the most important being the sulfated alcohols and alkyl aryl sulfonates.

The principal nonionic wetting agents are polyethylene oxides which are compatible with anionic and cationic types but which, unfortunately, can cause excessive foaming in certain circumstances. Both anionic and nonionic detergents have very good wetting, dispersing, and rinsing agents but are of little use against most deposits such as beerstone.

The cationic wetting agents are essentially quatemary ammonium compounds and are far more widely used as sterilants (sanitizers) than wetting agents. The high concentration of caustic soda limits the surfactant’s ability to couple and the result is the product will have a difficult time going into solution or hydrotroping.