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.
PART 1–GENERAL
1.01 SUMMARY
A. This procedure provides general guidelines for preserving and restoring the bare aluminum surface finish of decorative aluminum architectural features.
B. Decorative aluminum architectural features (bare, anodized, and conversion coatings) are frequently found with a variety of tooled finishes. Some types of aluminum finish textures found in historic buildings include the following: Embossed, sandblasted, wire-brushed or satin, or buffed/polished.
C. The best method of preserving the finish involves the application of a protective coating of lacquer or wax to prevent dirt and grime from accumulating.
D. See 01100-07-S for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections:
- Safety Precautions
- Historic Structures Precautions
- Submittals
- Quality Assurance
- Delivery, Storage and Handling
- Project/Site Conditions
- Sequencing and Scheduling
- General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing this procedure and should be followed, when applicable, along with recommendations from the Regional Historic Preservation Officer (RHPO).
E. For general information on the characteristics, uses and problems associated with aluminum, see 05010-08-S.
1.02 REFERENCES
A. Technical Report #C-6: “Aluminum and its Alloys,” The Aluminum Association, September 1978, fourth printing, February 1984.
B. Technical Report #92: “Care of Aluminum,” The Aluminum Association, February 1983.
C. “Metal’s in America’s Historic Buildings: Uses and Preservation Treatments”, U.S. Department of Interior - National Park Service - Preservation Assistance Division, Chapters 8 and 18, Revised 1993.
D. Aluminum Association, 900 19th Street NW, Ste. 310, Washington, DC 20006
1.03 MAINTENANCE
A. To clean a waxed surface simply wash with clean, clear water and wipe with clean cloth.
B. To remove yellowed wax, apply appropriate solvent with a clean cloth. If necessary, wash surface with mild soap and water and reapply wax after surface has dried.
C. Aluminum architectural elements should be protected by a non-absorptive, insulative coating to prevent direct contact with corrosive agents.
D. Aluminum architectural elements should be protected from rainwater run-off from wood and copper roofs and copper gutters.
PART 2–PRODUCTS
2.01 MANUFACTURERS
A. S.C. Johnson & Son, Inc. Carnu Street Racine, Wisconsin 53405 414/631-2000
B. E.I. duPont de Nemours & Co., Inc. 1007 Market St. Wilmington, Delaware 19898 302/774-1000
2.02 MATERIALS
A. Methacrylate type lacquer such as “DuPont 1234 or DuPont RK 935” (E.I. duPont de Nemours & Co.), or approved equal.
B. Ground pumice
C. Soft bristle brushes
D. 00 to 0000 stainless steel wool
E. Wax, most types including automotive and floor waxes without cleaners or abrasives such as “Beautiflor Liquid Wax No. 5951” and “Wax Emulsion” (S.C. Johnson & Son, Inc.), or “Dupont 7 New Car Wax” (E.I. duPont de Nemours & Co.), or approved equal.
PART 3–EXECUTION
3.01 EXAMINATION
A. Examine the surface to determine the extent of damage.
- If the damage is not severe, the aluminum elements can be protected from abrasion or erosion by coatings of lacquer, wax or suitable paint.
- If the damage is extensive, the deteriorated section(s) must be replaced with new metal of a heavier gauge, but which matches the existing in color, appearance, etc.
3.02 PREPARATION
A. Verify the finish prior to making repairs.
B. Remove all oil, dirt, and other debris from the surface.
3.03 ERECTION, INSTALLATION, APPLICATION
A. Restoring the surfaces of decorative aluminum architectural elements:
CAUTION: DO NOT RESTORE ANODIZED OR CONVERSION COATINGS
USING THESE METHODS - THEY WILL BE DAMAGED.
- Apply wax or lacquer according to the surface texture desired (see 1a-1d below). DO NOT allow coating to build up and discolor surface texture.
- For an embossed texture: Using a soft bristle brush, apply finish compound of ground pumice and water.
- For a sandblasted texture: Use light sandblasting (only under factory conditions).
- For a wirebrush or satin texture: Using a soft bristle brush, apply a finish compound of ground pumice and water.
- For a buffed or polished finish: Using fine stainless steel wool (0000 to 00), hand rub the surface with ground pumice.
- Follow manufacturer’s recommendations and procedures. Buff accordingly to achieve appropriate finish.