The equipment to carry out acrylic-total-impregnation of stone was installed in Bamberg in 1979. Technical difficulties occurred during the first years, such as fire and explosions in the impregnation tank, deposit of the polymer on the stone surface, darkening of the surface, cracking of the stone, insufficient impregnation. It has been possible to determine the causes of these failures and to eliminate them. The total impregnation process, when properly supervised, is recommended for consolidation of deeply weathered stone. -- AATA