Corrosion inhibitor
In a dishwasher detergent it is what stops the machine and the cutlery being attacked by the detergent.
In detail
A corrosion inhibitor is added to a cleaning product to protect the metal and glass it will contact from the product's own chemistry. Machine dishwashing is the clearest case: the wash is strongly alkaline and hot, which is what makes it effective against baked-on food and also what makes it aggressive towards aluminium, towards decorated glaze, and towards the machine's own components. Silicates are the classical inhibitor for this. They lay down a very thin protective film on metal surfaces, which is why alkaline machine detergents are formulated with them and why a strongly alkaline cleaner NOT designed for the job can attack an aluminium pan that survives the dishwasher. The class is one of those the detergent labelling regime and the functional-class taxonomies both recognise, and it is a good example of a formulation containing an ingredient whose whole purpose is to limit the effect of another.
Why
- Corrosion inhibitor is explained by Corrosion and passivation
- Corrosion inhibitor is explained by Alkali attack on light metals
Sources for this page
Sources
Safer Chemical Ingredients List — functional-use classes
United States Environmental Protection Agency (EPA), Safer Choice · Government or regulator
Relied on for: That the class is one of the functional-use classes a cleaning formulation is assessed in. (states this directly)
Handbook of Detergents (Surfactant Science Series)
CRC Press / Taylor & Francis · Reference work
Relied on for: That corrosion inhibitors such as silicates are formulated into alkaline machine dishwashing products to protect metal surfaces and machine components. (background and mechanism only)