What are builders used for?
Household water typically contains mineral deposits, mainly in the form of calcium and magnesium particles. This is a property called water hardness and it affects the cleaning power of detergents because the particles bond with the surfactants contained in detergents, preventing them from working properly. Builders are used to help improve the quality of water (called water softening), to help detergents work more efficiently.
How do builders work?
They soften water by binding to the calcium and magnesium ions in water, preventing them from reacting with other detergent ingredients. They can be thought of as the detergent warden – they round up the free ions and keep them away from the detergent particles, so that the detergent can do its job.
In addition to softening water, builders also neutralize body soils such as perspiration and help to remove stains that contain clay, dirt and fatty lipids. Some builders further improve cleaning performance by raising the pH of the wash water, making it more alkaline. This makes stains and surfaces negatively charged and thus there is more electrostatic repulsion between them, making stains easier to remove.
3 Types of builders
Sequestrating builders - e.g. Sodium citrate
These are soluble builders and form soluble compounds with magnesium and calcium.
Precipitating builders - e.g. Sodium carbonate
These are insoluble builders and form insoluble compounds with magnesium and calcium.
Ion exchanger builders - e.g. Sodium aluminosilicate
These builders replace the calcium and magnesium ions in wash water with other ions that will not impair detergent function.