**4.1 Hand-layup method**

Hand-layup method is also known as the wet-layup method. This process is the simplest process for the production of ballistic protection composites and is based on the application of materials in layers. The production of composites by this method is a combination of a polymer matrix reinforced mainly with fibers. The shape of the product depends on the mold used in which the layers of reinforcing fibers are placed, which are then saturated with wet (resin) by pouring over the fabric and pulling into the fabric. The resin is generally applied to reinforcing fibers or fabric with a roller. After applying the reinforcement to the resin matrix, the tool is left to harden the resin at room temperature or elevated depending on the type of matrix. The handlayup method is suitable for the production of smaller quantities and in the conditions of manufacture and acceptable for prototype production in which complex molding or other costs might be an issue. The hand-layup method is not suitable for highvolume applications and has high labor costs.

## **4.2 Vacuum bagging**

Vacuum bagging is an extension of the previously explained process by applying pressure to the laminate when it is laid to improve its consolidation. In this process, sealing of reinforcing fibers or fabrics is achieved. The air under the bag is extracted by means of a vacuum pump and in this way up to 1 atm of pressure can be applied to the laminate to solidify it. The main advantages of this process are higher fiber content laminates can usually be achieved than with standard hand-layup method, lower void content is achieved and better fiber wet-out due to pressure and resin flow throughout structural fibers, with excess into bagging materials, and the vacuum reduces the amount of volatiles emitted during cure. The disadvantages of the explained process are extra process costs, higher level of skilled operators needed, especially in mixing and control of resin content.
