U.S. General Services Administration
Technical Procedures Disclaimer
Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.
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We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.
This general checklist is an aid for inspecting the condition of cast iron. It should be used as a supplement to “Cast Iron: Characteristics, Uses and Problems”.
- Examine the overall surface condition and appearance, paying particular attention to horizontal surfaces. Look for cracks, crevices, pockets, folds or details in the metal which may collect and hold water.
- Examine and evaluate the coatings; determine the type and age of protective coating by visual or laboratory analysis. Look for:
- Cracks or breaks in the coating such as crazing, hairline cracks, cracks along seams, or other fractures in the surface, evidence of rust or rust stains at crazing, or blistering/flaking adjacent to cracks. Failures of this type may be one of the earliest warning signs of potential deterioration.
- Bubbles or blisters on the surface of the coating. This type of failure results from the separation of the protective coating from the substrate. When left unrepaired, these air pockets may trap water or moisture and may accelerate deterioration or produce corrosion. Waxes and oil coatings are not susceptible to blistering.
- Note extent of blistering and location of problem.
- Is the problem localized or general?
- Peeling and flaking of the surface. This usually results from unrepaired cracking or blistering (discussed above) and represents a more advanced stage of coatings failure. Areas left unprotected due to coatings loss may result in rust or corrosion.
- Note extent of peeling/flaking and location of problem.
- Is the problem localized or general?
- Erosion and wear of the surface. Carefully examine the coating as well as the bare metal.
- If possible, note all evidence of wear due to environmental or natural exposure.
- If possible, note all evidence of wear due to human exposure or vandalism.
- Graffiti on the surface.
- Note basic types of graffiti material used such as paint, greasepaint, lipstick, marker, etc.
- Note pattern of graffiti and location.
- Structural and mechanical deterioration. Look for rusting, cracks, breaks, etc. Monitor areas of concern to determine if they are active.
- Identify locations of broken pieces. Note if they are missing or salvageable. Label all recovered material to location.
- Identify locations of breaks at seams. Note whether connectors are missing or loose.
Reference
Margot Gayle, David W. Look, John G. Waite. Metals in America’s Historic Buildings. Washington: National Park Service, 1992
L. William Zahner. Architectural Metals: A Guide to Selection, Specification, and Performance. New York City: John Wiley & Sons, 1995.