At any given time, the stresses applied to each layer are the same and equal the mat pressure. While the total mat deformation is controlled by the press opening, the deformation in each layer is distributed according to its viscoelastic and elastoplastic properties, which are functions of temperature, moisture content, and degree of resin cure. Figure 6 shows predicted density profiles at various stages of pressing (Dai and others 2000). Before pressing, the mat density is assumed to be uniform in all layers. During press closing (Fig. 5), the layer deformations are calculated based on their stressñstrain relationships. The layer and overall mat densities in this stage incur the biggest increases. Particularly, the surface densities increase at