In this work, the authors show how to build a semi-industrial scale macrothermal analysis experimental apparatus for low-pressure aluminum casting AA354 with quasi-unidirectional solidification. Several thermocouples were connected to a multichannel electronic device allowing a sampling rate up to 10 Hz; the thermocouples were installed in the mold at different locations to acquire the discontinuous cooling curves at those same locations. With this type of experiment and appropriate mathematical procedures, it was possible to build a reasonable response surface T = f(x,t) and the respective derivatives: \( \partial T/\partial t \) and \( \partial T/\partial x \). Exponential polynomials were applied for modeling the curves and linear interpolation to relate the several cooling curves. Mathematical tools applied to the modeled curves allowed the authors to identify different solidification events and correlate them with the specific thermal gradient and cooling conditions.