This thesis provided a unique opportunity to evaluate the efficacy of a complex stone conservation treatment after 17 years of outdoor weathering. It is rare for a conservator to return to a site and assess her/his treatment and even rarer to monitor a treatment periodically over time. The conservation project under review was performed in 1993-94 and was documented step by step, including masonry characterization and condition assessment, treatment testing, treatment selection, and application. This abundance of information facilitates a comparative evaluation of the effects of the treatment on the masonry over time. This was made possible by the before, during and after treatment photographs, graphic conditions documentation, and the continued involvement of the Convento column's principal conservator.