The present invention related to a process to improve the adhesion between a thermosetting laminate and a thermoplastic shell in making reinforced plastic laminates for sanitary fixtures, such as shower receptors, spas, bathtubs, sinks, lavatories and the like, and composites laminates for transportation, marine, and construction applications. The adhesion improvement is through a designed post-curing process of the cured composites laminates. The thermosetting resin used in the construction of composites laminate can be unsaturated polyester resin of any kind, vinyl ester resin, or combination of both.