A range of permeation techniques were employed to investigate the transport mechanisms across polymer films cast from latices containing either no or only low levels of water soluble leachates such as residual surfactant from polymerisation or added plasticiser essential to film formation. Hydrophilic pathways can provide a mechanism of transport, in addition to partition into and solution-diffusion in the polymer phase. Loss of porosity by low T_g polymers on drying highlights the value of solute probes in studying film morphology.