<p>Precise measurement of active clay in molding sand is essential in the control of foundry green sand to maintain optimal properties of the green sand. Historically, active clay levels have been measured using the methylene blue (MB) test. A new alternative active clay test has been developed and tested, using a spectrophotometric technique that features advantages, including digital measurement of active clay in green sands, as well as a shorter and simpler testing procedure than the MB test. This measurement had only been previously applied to premixed standard sands and not sands from the active foundry environment. In this paper, we use this alternative test to measure more than 20 active foundry sands with varying active clay levels at three independent laboratories, and we also compare this alternative measurement with the MB test. It was demonstrated that the alternate test yields comparable active clay values to the MB test, while offering less measurement variance, both between operators and between laboratories. Additionally, a lower sample size can be used to perform the alternate test, suggesting the potential for automation of this alternative test in the future.</p>