Compositions and methods are disclosed for preventing or reducing frizzy appearance of keratin fibers, including hair, and reducing the amount of fly-away strands of hair, particularly in humid conditions, by forming a coating on hair that is resistant to water vapors from the air or surrounding environment. The compositions comprise a combination of a hydrophobic particulate material comprising a hydrophobically surface-modified aluminum oxide and one or more hydrophobic film formers in a cosmetically acceptable vehicle.本發明揭示尤其在潮濕條件下藉由在頭髮上形成對來自空氣或周圍環境之水汽具有抵抗性之塗層來預防或減少角蛋白纖維(包括頭髮)之捲曲現象及減少飄揚之髮束量的組合物及方法。該等組合物包含疏水性微粒材料與一或多種疏水性成膜劑在化妝品可接受之媒劑中的組合,該疏水性微粒材料包含疏水性表面改質氧化物。