[en] To develop better control of size, wall thickness, and shell quality, we have studied the physical and chemical transformations of metal-organic gels during heating, employing a number of thermal analytical techniques, such as pyrolysis-gas chromatography (PGC), pyrolysis-mass spectrometry (PMS), TGA, DTA, and hot stage microscopy. This work will be the basis for mathematical modeling of the shell blowing process. The residual blowing gases in the glass spheres and the volatile gas content of the metal-organic gels were analyzed. The effect of gel aging on these was also studied. The primary component of the residual gases in the spheres is 70%--80% carbon dioxide, with the balance oxygen and nitrogen; water has also been found in some cases. The potential volatiles in metal-organic gels depend on the aging history of the gel, and consist primarily of water, carbon dioxide, and a variety of organic species