Reinforced plastic resin-rich

Resin-rich area n. A region in a reinforced-plastic article in which there is an objectionable excess of resin. 

If the material is reinforced, such as a glass fiber-filled phenolic or polyester, relatively thin passages in the cavity may cause the low-viscosity plastic to flow into the passage, but may strain out the glass fibers resulting in a resin-rich, but inadequately reinforced (and, therefore, weaker) area in the final part. 

An exttemely smooth surface can be obtained on a reinforced plastic molding by placing a thin overlay sheet on the exposed surface of the composite. This type of mat provides little actual reinforcement. It does, however, facilitates a resin-rich surface layer to be incorporated into the molded part. 

Because in glass fiber reinforced plastics exposed to media, the fibers are particularly exposed to attack, they can be protected by a resin-rich layer (with few fibers). If this layer is at least 2.5 mm thick and contains not more than approx. 30% glass fibers, it is called a chemical protective layer. Facing the medium, a 0.3 - 0.6 mm thick layer should be as fiber-free as possible. A chemical protective layer may contain gelcoat- or non-woven layers. 

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