<p>The invention relates to the impregnation of wood by a solvent-free melt of modified natural resin which is solid at ambient temperature. Besides the modified natural resin, melts according to the invention may comprise wax and further additives. The melting point of the wax is preferably above 80 DEG C. The addition of wax elevates the softening point and reduces the viscosity of the melt. Melts according to the invention do not tend to discolor even at the given temperatures of the loading treatment so that the wood treated with a melt of modified natural resin mainly retains its natural appearance. <IMAGE></p>