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Historic Preservation - Technical Procedures

Spectitle:

Cleaning Exterior Copper Components

Procedure code:

0575001P

Source:

Developed For Hspg (Nps - Sero)

Division:

Metals

Section:

Ornamental Copper

Last Modified:

02/24/2012

Details:

Cleaning Exterior Copper Components



CLEANING EXTERIOR COPPER COMPONENTS


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on cleaning exterior
         copper architectural elements that are dirty, soiled, or
         discolored.

    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.   For additional information on the characteristics, uses
         and problems associated with copper, see 05015-01-S.

1.02 SYSTEM DESCRIPTION

    A.   Ornamental elements of copper are formed of very thin
         copper sheets.  They should be in good condition, without
         any signs of surface dirt, debris, soiling, or
         discoloration.


PART 2---PRODUCTS

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 adequate
    for stain removal work, and these products should be purchased
    when available, as they tend to be less expensive.  Common
    names are indicated below by an asterisk (*).

    A.   Copper Sulfate (CuSO45H20):

         1.   A sulfate of copper especially the normal sulfate
              that is white in the anhydrous form but blue in the
              crystalline hydrous form and that is often used as
              an algicide and fungicide.

         2.   Other chemical or common names include Cupric
              Sulfate; Blue stone*; Blue vitriol*; Roman
              vitriol*.

         3.   Potential Hazards:  TOXIC.

         4.   Available from chemical supply house, drugstore or
              pharmaceutical supply distributor, garden and lawn
              supply center, hardware store, swimming pool supply
              distributor, or water and sanitation supply
              distributor.

    B.   Nitric Acid (HNO3):

         1.   A corrosive liquid inorganic acid used especially
              as an oxidizing agent, in nitrations, and in making
              organic compounds such as fertilizers, explosives
              and dyes.

         2.   Potential Hazards:  CORROSIVE TO FLESH; CORROSIVE
              TO CONCRETE, STEEL, WOOD OR GLASS.

         3.   Available from chemical supply house or hardware
              store.

    C.   Clean, potable water

2.02 EQUIPMENT

    A.   Cellulose sponge mop or similar applicator

    B.   Clean soft wiping cloths

    C.   Heavy gloves and protective gear


PART 3---EXECUTION

3.01 ERECTION/INSTALLATION/APPLICATION

    A.   Mix 4 ounces of copper sulfate, 1/2 gallon of lukewarm
         water and 1/8 ounce of nitric acid.

         NOTE:  ABRASIVE AGENTS ARE NOT TO BE USED.

    B.   Apply the solution to the copper surface using a
         cellulose sponge mop or similar hand applicator.

         CAUTION:  AVOID APPLYING CLEANING SOLUTION TO METAL IN
         DIRECT SUN, AS IT BECOMES VERY HOT, AND THE DETERGENT OR
         SOAP SOLUTION WILL DRY IN STREAKS BEFORE IT IS POSSIBLE
         TO RINSE IT OFF.  THESE STREAKS CAN VERY EASILY BECOME
         PERMANENT AND CANNOT BE REMOVED WITHOUT ABRASION.

    C.   Thoroughly rinse the surface with clean, clear water and
         dry with clean, soft cloths.  Repeat the process as
         required to achieve the desired level of cleanliness.

                         END OF SECTION