Recycled soda-lime glass was successfully converted into glass foams by a particularly simple and economic processing, consisting of a direct heating of glass powders at temperatures from 900 to 1050 °C. The foaming operated by the oxidation of SiC, inserted as powder additive, was affected by a complex combination of processing temperature, soaking time, devitrification tendency and amount of MnO2, acting as oxidation promoter. A preliminary optimization of the processing parameters led to foams with a good microstructural homogeneity and mechanical strength. A following fundamental optimization was dedicated to the introduction of several waste glasses in the glass/SiC/MnO2 mixtures, aimed at modifying the glass viscosity and devitrification tendency, and led to improved foams, promising for industrial production.