Froth

Froth refers to a light, foamy mass produced when a liquid is agitated, aerated, or subjected to a chemical reaction that generates gas. It is a type of foam formed by gas bubbles dispersed in a continuous liquid phase. The term is often used for surface foams on beverages and natural scenes, but can apply to any system where gas bubbles are stabilized by surface-active agents.

Froth forms when nucleation sites create bubbles that grow and become numerous enough to form a cohesive layer. Factors such as surface tension, liquid viscosity, temperature, and the presence of stabilizers like proteins or surfactants influence the size, persistence, and drainage of the froth. More stable froths last longer, while agitation or drainage can cause them to collapse.

Natural froth appears as sea foam on ocean surfaces where waves trap air and organic matter. In culinary contexts, froth contributes to the head and texture of beverages such as beer, cappuccino, and hot chocolate; milk frothing uses steam or air to stabilize microbubbles that form a creamy layer. In industrial contexts, froth is exploited in froth flotation, a separation method that uses bubbles to lift hydrophobic particles from a liquid.

Additional everyday examples include foamy lather produced by soaps and shampoos, and visible foam in cleaning and personal care products. While related to foam, froth often denotes lighter, shorter-lived foams associated with liquids in motion or with rapid gas generation.