Grazing-incidence small-angle X-ray scattering (GI-SAXS) patterns were obtained from thin films of lipid/glycerol mixtures, spin-coated onto silicon wafers and exposed to a humidified helium or argon environment. The glycerol acts as a humectant; without it, formation of lipid cubic phases cannot be achieved unless extremely high (>98%) relative humidity is used, which is difficult to achieve in practice. In the presence of glycerol and reasonably high (>70%) relative humidity, the cubic phase adopts the excess water structure. This is confirmed by the lack of absences from the experimental GI-SAXS patterns, and by distinct micron-sized grains observed by AFM (see later, Figure ).