The process of press forming commingled yarn composites is studied and modelled based on the theory of porous media. Two sub processes are considered: (1) the wetting and compaction of individual bundles and (2) the overall preform deformation. An experimental method is introduced, to study these two sub processes separately. The experiment suppresses the fluid pressure build-up, and thus the process of wetting and bundle compaction, by draining the resin into a porous wall. In consequence, the measured response consists only of the preform contribution. Finally, the total response is simulated and tested against independent consolidation experiments. It was demonstrated that the present approach gives better predictions compared to models based on the bundle response only. © 2006 Elsevier Ltd. All rights reserved.