The flow table is a standardized test that is widely used to qualify a mortar to be tested for compressive strength and air content. It is also the only standard test to quantify a mortar workability property. Therefore, the calibration of this device is paramount and it is done today by preparing a mixture of silica powder and oil. Once the two materials are selected, they are mixed and tests are performed using the flow table at the Cement and Concrete Reference Laboratory (CCRL). This flow table is identical to commercial versions used in practice, and the values obtained with this flow table are considered the reference values that are used to calibrate all the flow tables in the United States (USA). This procedure is an empirical procedure and relies heavily on one device that could break or whose result can drift over time. This study will review the manufacture process of the reference material, provide historical data and then propose a more scientifically-based approach to developing a new reference material.