Museum artifacts made of polyurethane foam are frequently affected by conservation issues mainly related to the loss of their mechanical properties. While effective polyurethane ether foam treatments already exist, no convenient consolidation treatment exists for polyurethane ester foams. The possibility of a reinforcement effect expected to prevent the mechanical properties loss has been evaluated. Two aminoalkylalcoxysilanes (AAAS), the 3-Aminopropylmethyldiethoxysilane and the N-(2-Aminoethyl)-3-aminopropylmethyldimethoxysilane, which gave promising results for consolidation of paper, have been tested on modern industrial flexible polyurethane ester foam samples. AAAS solutions at different concentrations have been applied, by immersion, on polyurethane ester foam samples. Mechanical properties have been studied by Compression Force Deflection Test, which shows that after AAAS treatment the resistance of the foam to compression improves. The color of the samples before and after consolidation has been monitored to assess the impact of the treatment on the visual aspect of the foam. The AAAS distribution in the thickness of the samples has been investigated by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Magic angle spinning nuclear magnetic resonance (MAS NMR) has been used to confirm AAAS polymerization and to evaluate its average polymer chain length. The promising results obtained suggest that AAAS could be an efficient solution for the consolidation of polyurethane ester foams.