As part of the work involved in the conservation of a fresco by Hans Ernie at the Ethnographic Museum of Neuchâtel, the Laboratoire de Conservation de la Pierre of the Ecole Polytechnique Fédérale de Lausanne studied the possibility of consolidating the degraded lime coating with silicate esters. Four commercial products were tested. Their efficacy was verified experimentally, first mechanically, to check the water absorption rate and hydraulic dilation rate. In order to determine whether it was better to consolidate the coating before or after applying the colors an experiment was set up to simulate the action of rainfall, the main factor of degradation. The results obtained show that the consolidation of a lime mortar with low cohesion can be achieved with silicate esters. Undoubtedly the best process consists in applying the consolidant last, after the colors have been applied. -- AATA