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.
A. This procedure includes guidance on cleaning and oiling statuary bronze surfaces. For additional guidance on cleaning, polishing and protecting bronze, see 05010-01- R, 05010-24-R, 05010-06-P, 05010-07-P and 05010-04-P.
B. 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
- 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).
C. Cleaning and refinishing bronze is highly specialized and should be conducted under the supervision of a metals conservator. All chemicals and their application should be approved prior to use by the metals conservator to ensure protection of historic metals.
A. E.I. duPont de Nemours Co., Inc.
1007 Market Street
Wilmington, DE 19898
302/774-1000 or 800/441-7515
B. Atlantic Refining Company
C. 3M Consumer Products Group
St. Paul, MN 55133-3053
612/737-6501 or 800/364-3577
A. Standard Solvent:
- A mixture of 75% toluene, 24% acetone, and 1% butyl acetate (available from chemical supply firms).
- As an alternate, solvents normally used for thinning nitrocellulose lacquers, such as "DuPont Lacquer Solvent No. 3661-S" (for use in mid- temperatures, 50-80 F) (E.I. duPont de Nemours & Co., Inc.), or approved equal.
B. Mild Soap: Ivory or a mild detergent with pH of approximately 8.0.
C. Oil: "Lemon Grass Oil, Native E.I.," with a high grade distillate paraffin oil of c. 100 second viscosity, with a flash point above 350 F, containing napthenes but free of cracked stock such as kerosene, mixed 5 oz. "Lemon Grass Oil" per gallon of paraffin oil, "Topaz B" (Atlantic Refining Company).
D. Abrasive: Silicon carbide abrasive pads such as "Scotch- Brite" (3M Company) or standard commercially available pumice stone; or stainless steel wool. Do not use steel wool, which may promote discoloration of the bronze.
E. Oxidizing Agent: Aluminum chloride or liquid sulphur.
F. Cloth: Clean cotton waste.
A. Protection: Protect all masonry surfaces immediately adjacent to or below the area to be cleaned by covering with polyethylene sheeting.
3.02 ERECTION, INSTALLATION, APPLICATION
A. Wash the surfaces with mild soap and a soft cloth rubbing with the grain of the metal. Clean surface dirt and grease only, do not rub down to bright metal. Rinse thoroughly with clear water.
B. Remove all stains, oxides, sulfides or corrosion products with abrasive and standard solvent. Refinish areas of bright metal work with oxidizing agent, to match the existing cleaned statuary finish.
C. Remove cleaning residue with two applications of a standard solvent using a soft cloth. Apply oil to the surface, rubbing with a soft clean cloth, followed by a brisk rubbing with a second clean soft cloth to remove all excess oil. On irregular, molded surfaces, a soft fiber brush may be used as an applicator.