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.
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.
- Gayle, M., Look, D. and Waite, J. Metals in America's Historic Buildings: Uses and Preservation Treatments. Washington, DC: National Park Service, 1992.
- Zahner, L. W. Architectural Metal Surfaces.New York: Wiley 2004.
For guidance on cleaning nickel silver, see "General Methods of Cleaning Nickel Silver".
Characteristics of nickel silver
- A copper-nickel-zinc alloy that contains no silver.
- Contains 50-80 percent copper, 5-30 percent nickel and 10-35 percent zinc; it may also contain small percentages of lead, tin and manganese.
- Higher amounts of copper make the nickel silver metal more ductile and more resistant to corrosion.
- Higher amounts of nickel make nickel silver look more like silver.
- Higher amounts of zinc slightly improve corrosion resistance, lower the melting point, raise the nickel silver's strength and hardness, but decrease its ductility.
- Has many of the same characteristics as brass and bronze.
- Has existed for over 2000 years.
- May be wrought, cast, rolled, stamped, forged, drawn, extruded and machined.
- Silvery-white in color.
- Takes a high polish.
- Extremely hard.
- Highly resistant to environmental corrosion.
- Suitable for soldering and welding, depending on the presence of lead.
- Develops a protective oxide, or patina when exposed to oxygen; the patina is brownish-green when exposed for long periods of time.
- Called copper-nickel or false copper in the late 1600s due to the reddish color of the ore, but lacking the ductility and malleability of copper.
- Discovery that the silver ore contained nickel occurred in the mid-1700s; established as a new elemental metal by Aksel Frederik Cronstedt.
- A German version called new silver was marketed in the 1800s.
- Called German silver in England up until World War I; called nickel silver after that time.
Typical historical uses for nickel silver include:
- Nickel alloys commonly used for coins and ornamental objects.
- Tableware and plated objects.
- In the 1840s, nickel superseded copper as the material of choice for silver plating; nickel was harder, stronger and more durable than copper.
- Electroplating became the most fundamental application of nickel silver in the early 1900s; some uses included costume jewelry, keys, soda fountain and bar equipment, cigarette cases, automobile radiators and hub caps.
- Used for more decorative and structural elements in the 1920s, such as decorative panels, doors, grilles, railings, plumbing fixtures, plaques, trim and divider strips in terrazzo floors.
- Popular for door knobs, handrails and push plates because of its abrasion-resistance.
- Use of nickel silver declined in the 1950s.
- After World War II, stainless steel and aluminum replaced the use of nickel silver due to their low production cost.
- Most buildings containing nickel silver were constructed in the 1920s and 1930s.
Typical current uses for nickel silver include:
- Industrial and electrical purposes.
- Cast and wrought forms of the metal are occasionally found in building designs.
- Manufactured today only in silver-white or white with a yellow tint; shades of pale yellow, green, pink and blue can also be produced by varying the nickel content; custom orders can also be made to match an older nickel alloy finish if necessary.
Natural or Inherent Problems
- Corrosion: The zinc content of Nickel Silver makes the alloy metal sensitive to acid and sulfur pollutants and will tarnish in their presence.
- Stress Corrosion Cracking: Tensile strength combined with exposure to a corrosive environment; factors affecting this type of deterioration include temperature, metal composition and metal structure.
- Sensitive to chromic and nitric acids due to its high copper content.
Vandalism or Human-Induced Problems
- Scratches and dents.
- Susceptible to mechanical deterioration such as fatigue, but not creep.