Method of using a viscous printing ink for the protection of a notch formed in a skin which is intended for a part that is produced using a method including: producing a skin (1) having a notch (2) on the inner face thereof, covering the notch (2) with a protective element, and forming a foam (3) which is in contact with the inner face of the skin. According to the invention, during the notch-covering step, an ink having a viscosity that is at least equal to 0.6 St is applied to the notch (2) via printing and, subsequently, the ink is hardened such as to form a layer (4) that provides a bridge over the notch (2) without extending to the base thereof. The invention is suitable for motor vehicle instrument panels.