Abstract: A pressure can for dispensing polyurethane foams including a cylinder and a dome-like upper part with an opening therethrough. A closure member closes the opening and seals it and a valve body is inset in the closure member for dispensing the contents of the can. A can bottom covers the end of the cylinder opposite from the upper part and a piston is slidably disposed in the cylinder intermediate its ends for dividing the cylinder into a foam-former filling space between the piston and closure member and propellant space between the piston and the can bottom. The piston has a cylindrical depending skirt providing a gap between it and the cylinder wall sufficient to permit a limited amount of propellant to pass into the foam-former filling space but too restricted to permit the foam-former from passing from the foam-former space to the propellant space. The propellant dissolved in the foam former will flash when the filling is dispensed from the can at atmospheric pressure, creating bubbles to enhance foaming.