June 11, 2018, Monday - Preservation of Fire-Damaged Platteville Limestone Presentation at Mill City Museum

Time: 1 – 3 pm

Location: Mill City Museum, 704 Second Street S

Preservation of Fire-Damaged Platteville Limestone

The AIA of Minnesota welcomes you to join them on June 11 when Angela Wolf Scott from MacDonald and Mack Architects will present the current preservation work at the Mill City Museum that focuses on the technical aspects of analysis and treatment of fire-damaged limestone ruins.

The Washburn Crosby A Mill Complex is a National Historic Landmark on the Mississippi River in downtown Minneapolis. It was the epicenter of flour milling and innovation from the late part of the nineteenth century until 1965 when the site was no longer used for milling. The site suffered from multiple fires, but the February 1991 fire left the A Mill in a fragile state of ruins. In 1999 the site was redeveloped into commercial office space and the Mill City Museum. The most iconic part of the redevelopment is the Ruins Courtyard – a space that had been the northern half of the A Mill which is currently open-air and bound on three sides by the Platteville limestone ruins of the A Mill.

To improve their stewardship of the Washburn Crosby A Mill Complex, MNHS commissioned a Historic Structure Report on the complex with a key concern being a study of the ruins. Pieces of stone and mortar were routinely falling into the much-loved courtyard. The HSR included analyses of the characteristics of Platteville limestone in general but focused on the specific characteristics of the Platteville limestone of the ruins which had been exposed to fire; dramatic, thermal shifts; exposure to the elements; and modern, restoration products.

Armed with a more precise understanding of the physical properties of the stone and ruin walls, MNHS invested in the preservation of the ruins, approaching the work in phases. The physical preservation work uncovered and confirmed the academic research and analysis, making each subsequent phase more informed than the last.