The two most prevalent methods of preserving stone in Germany are discussed in this article: the silicic ester process and the impregnation with acrylic resin. These processes should only be selected with respect to the location and the condition of the stone to be treated. Preliminary examinations are a prerequisite for the first named process. Ascertaining the penetration and absorption properties of the hardening agent is especially important, because some stone has such thin capillaries, that it can only absorb very little and this only in the upper regions. Therefore, this process is suitable for stone whose surface sands off (not exfoliation) and is a part of the moisture absorption system of the building. The second method is suited for treating objects that stand apart and are not involved in the moisture absorption system of the building or can be removed and brought to an impregnating unit. In this process monomerous acrylate is introduced under pressure into the stone and polymerized within it. This method is suitable for stone in very poor condition, that is scaling, exfoliating or splitting.