Injection methods for the manufacture of fibre-reinforced plastics are performed using vacuum assistance and/or the application of pressure such as in presses or autoclaves to impregnate textile preforms. Within this article, the impregnation of textile preforms using a polyurethane spray coat method is examined. In contrast to conventional manufacture methods, the impregnation is performed using the expansion pressure of a polyurethane foam matrix. Further, the yarn impregnation of various composites is quantified with the help of grey value analysis of micrographs to evaluate the influence of the textile parameter and the fibre type.