A viscosity standard is needed to replace the National Institute of Standards and Technology (NIST) glasses currently being used to calibrate viscosity measurement equipment. The current NIST glasses are either unavailable or less than ideal for calibrating equipment to measure the viscosity of high-level waste glasses. This report documents the results of a viscosity round robin study conducted on the Defense Waste Processing Facility (DWPF) startup frit. DWPF startup frit was selected because its viscosity-temperature relationship is similar to most DWPF and Hanford high-level waste glass compositions. The glass underwent grinding and blending to homogenize the large batch. Portions of the batch were supplied to eight laboratories for viscosity measurements, which were conducted following a specified temperature schedule with a temperature range of 1150 degrees C-950 degrees C, with an option to measure viscosity at temperatures below 950 degrees C if their equipment was capable. Results were used to fit the Vogel-Fulcher-Tamman-Hesse and Arrhenius equations to viscosity as a function of temperature for the entire temperature range of 460 degrees C through 1250 degrees C as well as the limited temperature interval of similar to 950 degrees C through 1250 degrees C. The standard errors for confidence and prediction were determined for the fitted models.