Life and Death of A Milk Foam Film

Foams are fragile objects, often stabilized by either surfactants like soap or detergents, or by proteins such as milk protein casein or its derivative, sodium caseinate. Like all foams, frothy latte too dies away, and to a large extent, the life and death of foams is scripted by forces that drive drainage (thinning) and rupture of foam films that separate gas pockets. Here we show a snapshot of a single foam film undergoing drainage. As light reflected from two liquid-air surfaces shows thickness-dependent variation in interference intensity for films less than 100 nm (thinner is darker), the snapshots taken in ODES-lab, ChE, UIC show that film thickness has become inhomogeneous, and the emerging thick-thin regions organize into a flower-like pattern.