Stress functions have been used as a complementary tool to support experimental techniques, such as thermoelastic stress analysis (TSA) and digital image correlation (DIC), in an effort to evaluate the complete and separate full-field stresses of loaded structures. The need for such coupling between experimental data and stress functions is due to the fact that experimental techniques offer discrete information of stresses or displacements, e.g. isopachic stresses in the case of TSA, as well as unreliable data near edges. For TSA, additional information is needed to separate stresses, as it is often necessary for fatigue analysis and a general better understanding of structural integrity. This separation is often accomplished by using an Airy stress function, which stems from compatibility and equilibrium conditions, and is frequently represented in the form of an indefinite series of coefficients. To date, only ad hoc estimates for the number of coefficients necessary for accurate representation of a loaded structure are used, with the estimates being influenced by quality of experimental data, experimental noise, and complexity of loading and boundary conditions. Information presented here attempts to systematize the selection of the Airy stress function’s indefinite series coefficients relative to experimental thermographic data.