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Historic Preservation - Technical Procedures

Spectitle:

Cleaning And Polishing Bronze

Procedure code:

0501001P

Source:

Developed For Hspg (Nps - Sero)

Division:

Metals

Section:

Metal Materials

Last Modified:

02/24/2012

Details:

Cleaning And Polishing Bronze



CLEANING AND POLISHING BRONZE


ALL CLEANING REMOVES SOME SURFACE METAL AND PATINA.  THEREFORE, USE
CAUTION, AS EXCESSIVE CLEANING CAN REMOVE THE TEXTURE AND FINISH OF
THE METAL.

THE CLEANING OR STRIPPING OF METALS MAY INVOLVE THE USE OF
ABRASIVES, LIQUIDS OR SOLVENTS WHICH MAY SPLASH OR RUN OFF ONTO
ADJACENT MATERIALS.  TAKE SPECIAL CARE TO PROTECT ALL ADJACENT
MATERIALS, AND DO NOT USE THIS PROCEDURE ON METALS OTHER THAN
THOSE SPECIFIED IN THE SUMMARY.


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on the general cleaning
         of dirt and oil on bronze.

    B.   For general information on the characteristics, uses and
         problems associated with bronze, see 05010-03-S.


PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.   The Procter & Gamble Co.
         P.O. Box 599
         Cincinnati, OH  45202
         513/983-1100

    B.   Leo Silfen, Inc., Industrial Chemical Division
         525 Fourth Avenue
         Mt. Vernon, New York
         914/699-4800

2.02 MATERIALS

    NOTE:  When the common name of a chemical is used on the
    label, it is usually a sign that the substance is not as pure
    as the same chemical sold under its chemical name.  However,
    the grade of purity of the common-name substance is almost
    certain to be adequate for stain removal work, and because it
    is likely to be less expensive, the common-name product should
    be purchased when available.  Common names are indicated by an
    asterisk (*).

    A.   Mineral spirits:

         1.   Other chemical or common names include Benzine*
              (not Benzene); Naphtha*; Petroleum spirits*;
              Solvent naphtha*.

         2.   Potential Hazards:  TOXIC AND FLAMMABLE.

         3.   Safety Precautions:

              a.   AVOID REPEATED OR PROLONGED SKIN CONTACT.

              b.   ALWAYS wear rubber gloves when handling
                   mineral spirits.

              c.   If any chemical is splashed onto the skin,
                   wash immediately with soap and water.

         4.   Available from construction specialties
              distributor, hardware store, paint store, or
              printer's supply distributor.

    B.   Neutral detergent such a "Orvis" (Procter & Gamble), or
         approved equal.

    C.   Marine Type Metal Polish Formula 90 (Leo Silfen, Inc.,
         Industrial Chemical Division), or approved equal.

    D.   Clean, potable water

    E.   Lint-free wiping cloths

2.03 EQUIPMENT

    A.   Soft natural bristle brushes (non-metallic)

    B.   Wooden scrapers

    C.   Fine bronze wool -or- 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, AS IT MAY PROMOTE DISCOLORATION OF THE
         BRONZE.

    D.   Rubber gloves


PART 3---EXECUTION

3.01 ERECTION, INSTALLATION, APPLICATION

    NOTE:  WHEN CLEANING, TRY TO RETAIN THE BRASS PATINA, AS THIS
    PROTECTS THE BRASS FROM FURTHER CORROSION.  

    A.   Remove loosely adhered soiling, such as bird droppings,
         with wood scrapers before washing.

    B.   Remove more tenacious deposits with fine bronze wool.

    C.   Mix warm water (ONLY) with neutral detergent, or use
         proprietary metal cleaner.

         NOTE:  AVOID CLEANING BRONZE WITH ALKALINE SOAPS THAT DO
         NOT CONTAIN SODIUM HYDROXIDE, DETERGENTS CONTAINING
         PYROPHOSPHATES SUCH AS "TIDE" OR AMMONIA SOLUTIONS
         (ESPECIALLY ON LACQUERED SURFACES).  THESE WILL
         DETERIORATE THE COATING ON BRONZE.

    D.   Brush solution on bronze with soft natural bristle brush
         (no metallic bristles) or a lint-free cloth.  Rub along
         the grain of the metal.

    E.   If dirt is greasy, dilute cleaning solution 1:1 with
         mineral spirits.

    F.   Rinse thoroughly and dry with another lint free cloth.

    G.   Wash bronze periodically (twice a year) with a non-ionic
         detergent such as "Orvis" (Procter & Gamble).  Rinse with
         distilled water and wipe dry with a clean soft cloth, to
         prevent water spots and streaks.

    H.   For guidance on removing corrosion, removing lacquer and
         reapplying a protective coating, see 05010-31-R and
         05010-12-P.

                         END OF SECTION