Sodium Tripolyphosphate (STPP)
Soda ash is used in a number of soap and detergent products, but mainly in washing powders (heavy-duty detergents) or alone as washing soda crystals. Soda ash’s main functions are as a builder (see below) and as a water softener, but it also has a direct cleaning action.
Light soda ash is typically used in detergent powders, but dense soda ash is used in some countries where the physical properties of dense soda ash are preferred or where light soda ash is not readily available. Powder detergents are normally manufactured using either spray towers or fluid beds. Some spray towers are able to use either dense or light soda ash, while fluid beds tend to require light soda ash as feedstock.
Cleaning products have been used since ancient times, with soap dating to at least the Roman period. Synthetic detergents date from the end of the 19th century to the early 20th century; significant development occurred, particularly after the Second World War. Detergents, such as washing powders, comprise a number of essential ingredients. Surfactants lower the surface tension of water, allowing the water to wash materials more easily. Detergents also contain pH control agents, which can include soda ash. Other additives include bleaches such as sodium perborate or sodium percarbonate (the latter of which is made using soda ash), enzymes (to remove stains), and softeners. There are also fillers used as a bulking agent, for example, sodium sulfate.