Controlling foam in apparatus downstream of a melter by adjustment of alkali oxide content in the melter

Controlling foam in apparatus downstream of a melter by adjustment of alkali oxide content in the melter. One method includes feeding a feedstock into a submerged combustion melter (SCM) apparatus having an internal space containing a flowing or non-flowing molten mass of foamed glass comprising molten glass and bubbles entrained therein, the molten mass having glass foam comprising glass foam bubbles on at least a portion of a top surface of the molten mass. The molten mass from the SCM is routed to a downstream apparatus, stability of the glass foam in the downstream apparatus is observed, and alkali oxide percentage fed to the SCM apparatus is adjusted based on the observation to positively or negatively affect the foam stability. Systems for carrying out the methods, and the products of the methods are also considered novel and inventive.