The FECO sequence shown in Figure the BADGE/JeffAmine mixture changes as a function of time immediately after injecting 40 mL of DI water to the chamber. Injection of DI to the chamber saturates the box with water vapor, resulting in a 100 %RH curing environment within minutes. A small droplet of BADGE/JeffAmine was deposited on the top mount and brought into contact with the lower surface. Horizontal dark discontinuities (bands) are due to a refractive index mismatch between the BADGE/JeffAmine drop and air media. After approximately 2 minutes, the FECO lines begin to change shape and become diffuse (Figure and). Water diffuses into the BADGE/JeffAmine droplet almost immediately, dramatically changing the local refractive index of the BADGE/JeffAmine, B/JA. This is reflected and visualized in the distortion of the FECO in Figure D-F. It is reported that water uptake of epoxy resins follows a Fickian behavior, in which the initial stage of water uptake is a smoothly increasing function of the square root of time, t 1/2 , and where the thickness of the droplet determines the cross sectional-area through which water diffuses. Therefore, controlling the absolute surface separation as precise as possible is crucial to quantitatively compare environment effects on the cured BADGE/JeffAmine. Furthermore, undesired water diffusion during initial curing leads to water-induced plasticization, as also seen in other systems. Figure . A sequence of FECO fringes shows how water from the water-saturated environment diffuses into the BADGE/JeffAmine droplet within seconds. Time t = 0 is the time when water was introduced to the dry chamber. The water reservoir is located a few centimeters away from the surfaces. The rough shape of the fringe indicated non-uniform mixture of BADGE/JeffAmine and water, since the refractive index of water (Water ≈ 1.33) is significantly less than BADGE/JeffAmine (BADGE/JeffAmine ≈ 1.57). After 375 s the FECO fringes smoothen out again as the mixture becomes more uniform.