In this study, spontaneous capillary imbibition into an air-filled transparent etched silicon-glass micro model is investigated by optical imaging under ambient conditions for mixtures of ethanol and water. Images of the micro-model are acquired by a high-speed CCD camera. The binarized images allow us to obtain the overall imbibition kinetics and the time evolution of the phase distribution. A pore network with the structure parameters of the physical micro-model is generated, and a wetting algorithm that combines several pore-level liquid transport rules is developed to simulate the spontaneous imbibition of the liquid mixture into the network. The pore network simulations are able to reproduce the effects observed in the micro-model experiments. The influence of spatially correlated structural features on the imbibition dynamics is studied by further pore network simulations, and pore structures that cause weak or strong capillary imbibition are identified. The results of wetting simulations are shown for situations which cannot be treated by the Lucas Washburn equation. (C) 2016 Elsevier Ltd. All rights reserved.