Warpage Complex shapes of the finished part promote varying contraction rates relative to molded part dimensions and can cause internal stress to build up during the cool-down process during molding. This can cause warpage. Part warpage can be significantly greater than the in-plane mold shrinkage value. Water Absorption Water absorption is the percentage of increase in the weight of a plastic part during its immersion in water, or exposure to a humid air environment. Plastic parts absorb water by direct exposure or from airborne water vapors at a rate specific to each material.
Saturation is given by percentage of part dry weight.
Moisture in the resins before molding, unless removed by drying prior to processing, can cause serious degradation of physical properties.