The film-phase submodel accounts for the film growth chemistry on the tray surface. The film-phase submodel assumes an initial thin film of 10 µm on the tray surface due to imperfect cleaning. We assume that the tray liquid swells the film, so all the reactive sites on the film are in contact with the liquid-phase species absorbed in the film. The absorbed liquid-phase species reacts with the reactive site on the film to form covalent bonds to the film, resulting in film growth chemically. As the film grows thicker, the film growth can become diffusionlimited, such that only the reactive sites near the surface of the film are in contact with sufficient amounts of absorbed reactive liquid-phase species to react, which would effectively cap the growth rate as the film thickens.