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It is proposed that heating rate affects the apparent sintering temperatures of glass powders. The accumulation of thermal energy over time, or heat work (K s), is calculated over the range from the glass transition temperature to sintering temperature with the logarithm of time for heating rates from 1 to 60 K/min. The required heat work is independent of heating rate for two silicate glass powders but shows a decreasing heat work requirement for increasing heating rates for a borosilicate glass powder. Small cylindrical powder compact samples were used to minimize heat-transfer problems and were observed thermoanalytically using a hot-stage microscope. The densification temperature, defined as the peak in the shrinkage versus temperature curve, increases with increasing heating rate and is sensitive to the initial compact density. The use of mechanically pressed compacts with similar compact densities minimizes the contribution of initial density, allowing the comparison of sintering behavior as a function of heating rate.