A process for producing insulating foam, wherein certain especially small inorganic minerals such as silica fume are directly integrated into bubble fluid to better mechanically strengthen bubbles formed and thus allow the formation of smaller bubbles to be reformed. The manner of reforming the bubbles is progressive and actualized by a glass bead chamber, a second stage consisting of two screened discs, separated from each other and located at the end of the glass bead chamber, and a third stage chamber presenting itself with a considerably enlarged screen area and having considerably finer meshes than the second stage.