In structural materials and composites based on thermo set matrices, it is important to control reactions related to the cross-linking network. A fully cured system appears when a physical properties become non-variable and reach a plateau such as Tm, Tg, hardiness, etc.

The gel time is defined as the time when a liquid resin (open time) starts to form micro gels, before the gelatin (initial cure) and the formation of solid state (final cure). Above this time, processing cannot be properly done. Therefore, it is important, when processing a composites, to be able to measure and control the gel time.

We discuss on this chapter about the possibility to regulate the gel time according the domain concerned, that is, Marine and Aerospace applications.