This project explores methods for the removal of limewash from overpainted plaster surfaces, testing whether ion exchange resins can be used to safely clean these historic materials. The study utilizes the interior architectural finishes of the Capilla de Nuestra Señora del Rosario in Iglesia San José in San Juan, Puerto Rico to investigate the properties and efficacy of ion exchange resins when applied to chalking matte paints on lime plaster. Built in the 16th century, Iglesia San José is considered the second oldest church in the Americas. In 1998, a loss of structural integrity forced the closure of the building to the public. Today, through support from the WMF and an international team of conservators, conservation and restoration efforts progress at the church. The 17th-century Capilla de la Virgen del Rosario possesses the most extensive of the church’s remaining mural works. Current work in the chapel focuses on exposing the first mural campaign (Campaign A). Previous site work tested mechanical means of removal, which left behind a lime haze and proved aggressive on fragile plaster surfaces and powdering matte paints. Chemical methods, on the other hand, have not been tested. On fragile plaster surfaces, ion exchange resins may clean more effectively and cause less damage than mechanical methods. Current conservation literature shows little testing of ion exchange resins for their efficacy in removing limewashes or overpaintings, or their effects on calcium-rich substrates. This method requires further testing to determine if it is a cost- and time-effective restoration technique for large-scale applications.