The Maintenance and Repair of Architectural Cast Iron

house behind gates

As an architectural metal, [cast iron] made possible bold new advances in architectural designs and building technology, while providing a richness in ornamentation. (John G. Waite, with Historical Overview by Margot Gayle, The Maintenance and Repair of Architectural Cast Iron, 27 Preservation Briefs, U.S. Department of the Interior, National Park Service & New York Landmarks Conservancy)

Previously, in the first of the series on preservation briefs, we focused on the maintenance of historic concrete. This week, we will take a look at the maintenance of architectural cast iron.  Cast iron became cost effective with manufacturing techniques introduced in the Industrial Age, and its fire-resistance made it especially attractive in large urban areas.

The 19th century left us with a rich heritage of new building methods, especially construction on an altogether new scale that was made possible by the use of metals.  Of these, cast iron was the pioneer, although its period of intensive use lasted but a half century.  Now the surviving legacy of cast-iron architecture, much of which continues to be threatened, merits renewed appreciation and appropriate preservation and restoration treatments. (Waite & Gayle, 1991, p. 3)

Mississippi is home to a number of examples of iron store fronts, including those manufactured by Mesker Brothers, as well as other examples from Jones-McIlwain Iron Works in Holly Springs and Chickasaw Iron Works in Memphis.  The c. 1855 Rumble & Wensel Warehouse, remodeled 1892-97, in historic downtown Natchez is an excellent example (MDAH, HRI database).

Cast iron store front Natchez

100 Main Street, Natchez’ “finest cast iron facade.” Retrieved from https://www.loc.gov/resource/hhh.ms0177.photos/?sp=1, Historic American Buildings Survey, Library of Congress.

From Alcorn State, these stunning cast iron stairs are another fine example from HABS.  According to the Mississippi Department of Archives and History, the steps were formerly from “Windsor,” of the Windsor Historic Ruins, whose Corinthian column capitals are cast iron and are currently undergoing stabilization.

Alcorn cast iron steps

One of the most splendid examples of cast iron in Mississippi is found inside the old Warren County Courthouse.  You can see photographs of the staircase and judge’s dais along with a number of others at Going Inside: Old Warren County Courthouse.

Cast iron was considered structural as well as decorative.  Building fronts, columns, domes and cupolas, and lightcourts and skylights were structural.  Decorative cast iron included stairs, elevators, lintels, grilles, verandas, balconies, railings, fences, cresting, street furniture, lighting, fountains, statues, and tombs (Metals in America’s Historic Buildings, M. Gayle, D. W. Look, & J. G. Waite, 1992, National Park Service).

Two Oxford examples are included in the slide show below; admire a few other state examples before digging in to maintenance, repair and preservation of these important architectural examples.

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Maintenance and repair must conform to local building codes, environmental protection, and be done by experienced and qualified workers using protective equipment, under the guidance of a preservation architect. In other words, “do not attempt this yourself”: It is a job meant for pros. 

What are some of the tell-tale signs of deterioration?

  • Rust, missing elements, damage, structural failure, broken joints, damaged connections, and loss of anchorage in masonry

As with many materials (concrete, masonry, wood for example), exposure to moisture is a factor, and particularly with corrosive agents: sea water, salt air, acids, acid precipitation. Architectural details that trap moisture also increase the speed of rusting, and rust on the surface furthers corrosion.

As with historic concrete, assessment and planning is an essential step in maintenance and repair. Understanding the condition of the iron requires a physical inspection of construction, bolts, fasteners, brackets, etc., and may require removal of a section of paint to appropriately determine the condition of these important elements. Load-bearing elements must be assessed. In Mississippi, support columns and beams are the most common cast iron elements that I have run across.  While some are in good repair, others are in varying stages of neglect.  Preservation and maintenance of those columns and beams is essential in order to ensure they are performing as designed: load-bearing support for the building.

Preservation includes a variety of tasks, including cleaning and paint removal, which can range from simple to complex, painting and coating, caulking, patching, and mechanical repairs, and only if absolutely necessary when features are missing or corroded or damaged beyond repair, duplication and replacement (Waite, 1991).

A successful maintenance program is the key to the long term preservation of architectural cast iron. Regular inspections and accurate record-keeping are essential.

For additional history and photographs about cast iron architecture, see:

 



Categories: Architectural Research, Historic Preservation, MS Dept. of Archives and History, National Park Service

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6 replies

  1. Great post. The example in Hushpuckena actually has the foundry’s shipping stencil still visible on its side. I’ve got a photograph of it somewhere… :)

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  2. W. T. Adams Machine Co. in Corinth was another Mississippi company that manufactured cast iron architectural features, often marking their cast iron support columns for easy brand identification. The Curlee Block/Liddon Building’s storefront (sadly altered) is likely their work, though the columns are not marked.

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  3. Please understand the difference between ‘cast’ and ‘wrought’ iron. Structural beams are not normally cast iron. Steel picket fencing is not (normally) cast iron. Before attempting to write specifications for repair and restoration, you need to know the metal and or composition metal that requires repair. I certainly question ‘caulking’ cast iron where it has rusted as appropriate.

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    • Thank you for your reply, Ms Perry. Please let me clarify that all the information in this post was either directly quoted or paraphrased from the sources referenced and linked, primarily, the National Park Service’s Brief. I will check that brief again to ensure I did not misquote or misinterpret any information in those extensive guidelines, and if so, will be happy to add an addendum correcting any errors that may be mine.

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  4. Caulking is used to prevent rust, not repair rust.

    According to John G. Waite, AIA who wrote the Preservation Brief for the US Department of the Interior National Park Service Cultural Resources, Caulking, Patching, and Mechanical Repairs section, p. 10,
    “Most architectural cast iron is made of many small castings assembled by bolts or screws (Fig. 16a). Joints between pieces were caulked to prevent water from seeping in and causing rusting from the inside out. Historically, the seams were often caulked with white lead paste and sometimes backed with cotton or hemp rope; even the bolt and screw heads were caulked to protect them from the elements and to hide them from view. Although old caulking is sometimes found in good condition, it is typically crumbled from weathering, cracked from the structural settlement, or destroyed by mechanical cleaning. It is essential to replace deteriorated caulking to prevent water penetration. For good adhesion and performance, an architectural-grade polyurethane sealant or traditional white lead paste is preferred.

    Water that penetrates the hollow parts of a cast-iron architectural element causes rust that may streak down over other architectural elements. The water may freeze, causing the ice to crack the cast iron. Cracks reduce the strength of the total cast-iron assembly and provide another point of entry for water. Thus, it is important that cracks be made weathertight by using caulks or fillers, depending on the width of the crack.”

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