A photon-transmission method was used to monitor the evolution of transparency during film formation from various polystyrene (PS) particles which were produced using different steric stabilizers, that is, poly(acrylic acid) (PAA), poly(vinyl alcohol) (PVA), and polyvinylpyrrolidone (PVP). The latex films were prepared from PS particles at room temperature and annealed at elevated temperatures in various time intervals above the glass transition (T-g). To simulate the latex film-formation process, a Monte Carlo technique was performed for photon transmission through a rectangular lattice. The number of transmitted (N-tr) photons were calculated as a function of particle-particle interfaces that disappeared. The increase in the transmitted photon intensity (I-tr) was attributed to the increase in the number of interfaces that disappeared. The Prager-Tirrell (PT) model was employed to interpret the increase in crossing density at the junction surface. The backbone activation energy (Delta E) was measured and found to be around 120 kcal mol(-1) for a diffusing polymer chain across the junction surface for all PS latex films. (C) 1998 John Wiley & Sons, Inc.