The method for hardening electro-insulating materials is characterised by the utilization and/or co-utilization of near-infrared radiation (NIR) having a wavelength of 500 nm to 1400 nm. NIR also enables very fast hardening of the component surface even with pure thermally hardenable impregnating material and further provides good hardening of thick layers located deep inside said layers. Combined hardening, for example, NIR and UV light, is also possible.