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Historic Preservation - Technical Procedures

Spectitle:

General Method Of Cleaning Nickel Silver

Procedure code:

0501002P

Source:

Hsr - Federal Bldg/P.O., Wash, Dc - Bldg Conservation Tech

Division:

Metals

Section:

Metal Materials

Last Modified:

02/24/2012

Details:

General Method Of Cleaning Nickel Silver



GENERAL METHOD OF CLEANING NICKEL SI= LVER


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 cleaning nicke= l
         silver building features to remove surfa= ce dirt and
         grease.

    B.   Nickel silver is a nickel alloy usually containing 75%
         copper, 20% nickel and 5% zinc.  So= metimes tin and lead
         are also added to improve the casting properties of the
         metal.

    C.   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 Precaution= s

         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).

1.02 SUBMITTALS

    A.   Samples:  Clean a representative sample area using
         materials and methods specified at locat= ion specified by
         the Contracting Officer. The samples accepted by the
         Contracting Officer to serve as standard for the entire
         job. They will be marked and left undist= urbed.


PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.   Fisher Scientific Company
         711 Forbes Avenue
         Pittsburgh, PA  15219
         800/388-8355 or 412/562-8300

    B.   Ashland Chemical
         4550 N. East Expressway
         Doraville, GA  30340
         404/448-7010

    C.   E.I. DuPont de Nemours Company, Inc.
         Wilmington, DE  19898

    D.   GAF Corporation
         1361 Alps Road
         Wayne, NJ  07470
         201/628-4127

2.01 MATERIALS

    NOTE:  Chemical products are sometimes sold under a common
    name.  This usually means that the substance is not as pure as
    the same chemical sold under its chemical name.  The grade of
    purity of common name substances, however, is usually adequa= te
    for stain removal work, and these products should be purchas= ed
    when available, as they tend to be less expensive.  Com= mon
    names are indicated below by an asterisk (*).

    A.   Degreaser/standard solvent such as turpentine, phosphoric
         acid alcohols, mineral spirits or vinega= r.

         1.   Phosphoric Acid:

              a.   A syrupy or deliquescent tribasic acid used
                   espec= ially in preparing phosphates (as for
                   ferti= lizers), in rust-proofing metals, and as
                   a flavoring in soft drinks.

              b.   Other chemical or common names include
                   Ortho= phosphoric acid.

              c.   Potential Hazar= ds:  CORROSIVE TO FLESH;
                   CORRO= SIVE TO CONCRETE, STEEL, WOOD OR GLASS.

              d.   Available from chemical supply house or
                   hardw= are store.

         2.   Mineral Spirits:

              a.   A petroleum distillate that is used especially
                   as a paint or varnish thinner.

              b.   Other chemical or common names include
                   Benzi= ne* (not Benzene); Naphtha*; Petroleum
                   spiri= ts*; Solvent naphtha*.

              c.   Potential Hazar= ds:  TOXIC AND FLAMMABLE.

              d.   Safety Precauti= ons:

                   1)   AVOID REPEATED OR PROLONGED SKIN CONTACT.

                   2)   ALWAYS wear rubber gloves when handling
                        mineral spirits.

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

              e.   Available from construction specialties
                   distr= ibutor, hardware store, paint store, or
                   print= er's supply distributor.

         3.   Vinegar:

              a.   Potential Hazar= ds:  CORROSIVE TO CONCRETE,
                   STEEL, WOOD OR GLASS.

              b.   Available from grocery store or supermarket.

              c.   Vinegar itself, which contains about 4% acetic
                   acid, may be suitable for some purposes
                   requi= ring acetic acid.

         -OR-

         A mixture of 75% toluene, 24% acetone, and 1% butyl
         acetate (Fisher Scientific Company), (Ashland Chemical),
         or approved equal.

         -OR-

         Use a solvent normally used for thinning nitrocellulose
         lacquers, such as DuPont Lacquer Solvent No. 3661-S (E.I.
         DuPont de Nemours Company, Inc.) for use in
         mid-temperature 50-80=F8F, or approved equal.

    B.   Non-ionic detergent such as "Zyfo", "Tergitol" (Ashland
         Chemical), "Igepal 630" (GAF Corporation), or approved
         equal.

         1.   "Zyfo" cleaner conce= ntrate, a controlled suds,
              silicate buffered, non-io= nic, rinseless-type
              synthetic detergent, containing no soap, free
              alkali, solvents, abrasiv= es, acids, caustics or the
              like.

    -OR-

         Try the following cleaning solution:

         1.   7.5% thiourea solution (CS(NH2= )2):

              a.   A colorless crystalline bitter compound
                   analo= gous to and resembling urea that is used
                   espec= ially as a photographic and organic
                   chemi= cal reagent.

              b.   Available from photographic supply distributor
                   (not camera shop).

         2.   1% concentrated sulfuric acid<= br>
         3.   0.5% detergent and wetting agent

         4.   91% water; potable, non-staini= ng and free of
              materials detrimental to surfaces being cleaned

         CAUTION:  AVOID AQUEOUS AMMONIA, AMMONIUM SALTS (SCC),
         HYDROGEN PEROXIDE (>10%) OR OXIDIZING ACIDS.

    C.   Corrosion Inhibitor/Cleaner:  1% Benzotriazole solution
         in warm water - 40 g. Benzotriazole per gallon of water
         (Fisher Scientific Company), or approved equal.

    D.   Clean, potable water

    E.   Distilled water

    F.   Clean, soft cloth

    G.   Plastic sheeting


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.   Using a clean, soft cloth, wipe the surface with          degreaser, rubbing with the grain of the metal.  Clean
         surface dirt and grease only, do not abrade the metal.

    B.   Wipe the surface with clean, soft cloth soaked with non-
         ionic detergent or cleaning solution (see Section 2.02 B.
         above), working a small area at a time.

    C.   Rinse the cleaned area with distilled water to remove
         traces of cleaner and corrosion products which can
         precipitate soon after cleaning.

    D.   Dry with a soft cloth.

    E.   After completion of cleaning, apply corrosion
         inhibitor/cleaner on a clean soft cloth and rub along the
         grain of the metal.

                         END OF SECTION