Core Issue: Slow filling allows glass fibers to migrate to the surface of the molded part. Check mold venting—insufficient venting can limit. Discussion in ' Fiberglass and Composite Boat Building ' started by mrdebian, Dec 19, 2022. As per title, one of my friends who came to help me on a project made a mistake and instead of 1. This issue not only affects the visual appearance of the product but can also negatively impact. Adding glass fiber, toughening agent and other fillers to nylon can significantly increase the mechanical properties of the material. The. Life is 10% the cards you are dealt, 90% how you play em You will need to build that area back up.