An apparatus is disclosed for enhancing the mixing of foam precursors in foam-in-bag precursor systems, to thereby enhance the quality of the resulting foam. The apparatus comprises a heated chamber for storing bags containing the precursors in separate compartments, an opening for dispensing the heated bags, and mechanical agitators for externally agitating the bag containing the separated foam-forming precursors to mix the precursors and form foam. Also, a foam cushion packaging precursor is disclosed and comprises such a heated bag.