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Historic Preservation - Technical Procedures

Spectitle:

Cleaning And Oiling Statuary Bronze Surfaces

Procedure code:

0501022R

Source:

National Capitol Region Specifications

Division:

Metals

Section:

Metal Materials

Last Modified:

02/24/2012

Details:

Cleaning And Oiling Statuary Bronze Surfaces



CLEANING AND OILING STATUARY BRONZE SURFACES


PART 1---GENERAL

1.01 SUMMARY

    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:

         1.   Safety Precautions

         2.   Historic Structures Precautions

         3.   Submittals

         4.   Quality Assurance

         5.   Delivery, Storage and Handling

         6.   Project/Site Conditions

         7.   Sequencing and Scheduling

         8.   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.  


PART 2---PRODUCTS

2.01 MANUFACTURERS

    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
         Box 33053
         St. Paul, MN  55133-3053
         612/737-6501 or 800/364-3577

2.02 MATERIALS

    A.   Standard Solvent:
   
         1.   A mixture of 75% toluene, 24% acetone, and 1% butyl
              acetate (available from chemical supply firms).
         
         2.   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.


PART 3---EXECUTION

3.01 PREPARATION

    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.

                         END OF SECTION