Foam and aeration control agents control internal porosity and bubbles. They include blowing agents, aerators, and deaerators.
Aerators or air entrainment agents are chemical additives that insert air bubbles and pockets into a formulation, typically to remove odors, tastes, minerals, or carbon dioxide from a water-based mixture. This is accomplished by a scrubbing action, which occurs when a dissolved gas encounters the air, and by oxidation.
Foaming agents act in opposition to aerators; they introduce a gas to a liquid, which usually results in a foam. Detergents and surfactants are common foaming additives which reduce the surface tension of a liquid. A blowing agent initiates a reaction with other materials to produces a gas or vapor, which increase the compound volume and reduces density.
Defoamers and deaerators release entrapped air or prevent the formation of foam within a liquid compound. They are usually oil, silicone, or alcohol-based and are used in many industrial processes where air bubbles can damage machinery or surface coatings.
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