Window core colors in the context of window joinery play an important role in the aesthetics and durability of windows, especially those made of PVC (PVC). Window core is the internal color of the material from which the window frame is made. In practice, this core remains invisible, as windows are usually covered with special decorative films that give them their final appearance. However, the choice of the core color affects the aesthetics of the window in situations where the window is opened or there is damage to the window surface.