Organically-modified silica gels prepared by the sol-gel method are called "melting gels" when they show the behavior that they are rigid at room temperature, but soften and re-soften at temperatures in the range 100-120°C. Melting gels can be used to form glass seals at temperatures lower than conventional, all-inorganic glasses. Unlike most sol-gel glasses, melting gels are nonporous. After consolidation at > 135°C, melting gels no longer re-soften. In this study, melting gels were prepared using methyltriethoxysilane (MTES) and dimethyldiethoxysilane (DMDES), with five compositions between 50 mol% MTES-50 mol% DMDES and 75 mol% MTES-25 mol% DMDES. Thermal gravimetric analysis and differential scanning calorimetry were performed, along with FT-IR and Raman spectroscopic analyses. A helium leak test was performed and the measured helium transmission rate was ̃8.6 10 -5 cm3/day. In addition, 5x5 cm2 foil envelopes were filled with an organic electrolyte and sealed with melting gel. The envelopes were stored for 3 weeks at 70°C, and the measured weight loss was less than 1%.