A spout, system, and method for producing a foam from a pressurized mixture of a liquid containing gas bubbles, e.g., air bubbles. The spout consists of a spout enclosure defining the body of the spout, and which receives the pressurized mixture and conveys the foam out of the spout enclosure. The spout enclosure houses a plurality of screens disposed in series that successively screen the pressurized mixture. Each screen is separated from a consecutive screen by a screen spacing. The screening of the pressurized mixture progressively transforms the gas bubbles in the liquid into foam bubbles of a smaller and generally uniform size. The system uses a manifold having a plurality of intakes which introduce under pressure into a chamber gas, and a solute, solvent or liquid, thereby generating the pressurized mixture containing gas bubbles. This mixture is conveyed out of the chamber via an outtake to the spout enclosure.