The state of the art of foam stability is presented and applicability to specific problems in glass melts is discussed. The experimental part offers three measuring methods for the quantitative evaluation of foaming behaviour on glass melts: the direct observation of foam decay; stability investigations on single lamellae, and life measurements of single bubbles, in all cases as functions of various parameters such as temperature and composition of the furnace atmosphere. Experimental findings demonstrate that foam decay on glass melts occurs through the sequence of a drainage and a tear process. Probably the tearing of lamellae at the foam surface is rate determing. A general theory of foam stability cannot yet be developed at this time, however, some recommendations for plant practice can be derived from the results.
