Detergent builder
- Also known as
- builder
A detergent builder is an ingredient that improves a detergent's cleaning, mainly by softening the water: it removes or ties up calcium and magnesium ions that would otherwise interfere with the surfactants. Builders also often supply alkalinity and help keep removed soil suspended.
What is a detergent builder?
Hard water contains calcium and magnesium ions. These ions react with many anionic surfactants, making them less effective or causing them to precipitate, and they help bind soils to fabrics and surfaces. A builder counteracts the hardness so the surfactants can do their job, boosting overall detergency.
How builders work
Builders reduce hardness in one of three ways:
- Sequestering: binding hardness ions in soluble complexes. Chelating agents and phosphates work this way.
- Precipitating: forming insoluble salts that remove the ions from solution, as sodium carbonate does.
- Ion exchange: swapping hardness ions for sodium, as zeolites do.
Many builders also raise and buffer pH, which helps remove fatty and acidic soils, and help prevent soil redeposition.
Common builders
- Phosphates, such as sodium tripolyphosphate, once the dominant builder. Because phosphorus contributes to algae growth in lakes and rivers, their use in U.S. household laundry detergents was phased out in the 1990s, and many states restricted them in household automatic dishwashing detergents starting in 2010.
- Zeolites, insoluble aluminosilicates that exchange ions.
- Sodium carbonate (soda ash) and sodium silicates.
- Citrates, common in liquid detergents.
- Polycarboxylates and other polymers, often used as co-builders.
Frequently asked questions
Some builders, such as zeolites and large amounts of carbonate, are insoluble or hard to keep stable in liquids, so liquids tend to rely on soluble builders such as citrates.
Not all. Products used in soft water, or surfactant systems that tolerate hardness well, may need less builder.
Sources
- Cleaning product ingredient information, American Cleaning Institute
- Surfactants and Interfacial Phenomena, 4th edition, M. J. Rosen and J. T. Kunjappu, Wiley, 2012