Abstract: Disclosed is a cellular glass product having a density D at ambient temperature of at most 200 kg/m3 and a process for the production of a cellular glass product having a density D at ambient temperature of at most 200 kg/m3. The process comprises the steps of: a) contacting glass powder with foaming agent to form a dry mixture, b) thermally treating the mixture in a foaming furnace, thereby forming cellular glass, and c) annealing the cellular glass of step b) in an annealing lehr, wherein the concentration of at least one of the reagents in the dry mixture of step a) that are necessary for enabling the foaming reaction is at least 150% of the concentration corresponding to the theoretical minimum requirement for obtaining the density D.