Results of experimental investigations aimed at testing efficiency-related aspects of thermally induced degenerate four-wave mixing in absorbing solutions are reported. The effects of fluorescence, read beam time delay, and forward beam angle variations are measured and shown to strongly influence the achievable thermal grating diffraction efficiency. In particular, a strong decrease of conjugation efficiency is observed as a function of increasing angle between the forward beams. Conjugate beam diffraction efficiencies as high as 17 percent were measured for the dye RhB in acetone. Based on our observations, we predict that still higher conjugation efficiencies will be feasible under optimal conditions with the thermal grating mechanism.