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Historic Preservation - Technical Procedures

Spectitle:

Poulticing Copper/Bronze Stains From Brick Masonry

Procedure code:

0421106R

Source:

Tech Notes On Brick Construction - 20

Division:

Masonry

Section:

Brick Unit Masonry

Last Modified:

07/30/2013

Details:

Poulticing Copper/Bronze Stains From Brick Masonry



POULTICING COPPER/BRONZE STAINS FROM BRICK MASONRY


THE CLEANING OR REMOVAL OF STAINS FROM MASONRY MAY INVOLVE THE
USE OF LIQUIDS, DETERGENTS OR SOLVENTS WHICH MAY RUN OFF ON
ADJACENT MATERIAL, DISCOLOR THE MASONRY OR DRIVE THE STAINS DEEPER
INTO POROUS MASONRY.  USE THE PRODUCTS AND TECHNIQUES DESCRIBED
HERE ONLY FOR THE COMBINATIONS OF DIRT/STAIN AND MASONRY SPECIFIED.


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on removing
         copper/bronze stains from brick masonry.

    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).


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.   Ammonium Chloride - salt-like substance (NH4Cl):

         1.   A white crystalline volatile salt that is used in
              dry cells and as an expectorant.:

         2.   Other chemical or common names include Ammonium
              hydrochloride; Chloride of Ammonia*; Hydrochloride
              of Ammonia*; Muriate of Ammonia*; Sal Ammoniac*.

         3.   Potential hazards:  TOXIC; CORROSIVE TO FLESH;
              CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS.

         4.   Available from chemical supply house, dry cleaning
              supply distributor, drugstore or pharmaceutical
              supply distributor, or hardware store.

         -OR-

         Aluminum Chloride:  Available from chemical supply house,
         drugstore or pharmaceutical supply distributor.

    B.   Ammonia water:

         CAUTION:  DO NOT MIX AMMONIA WITH CHLORINE BLEACHES, A
         POISONOUS GAS WILL RESULT!  DO NOT USE BLEACH ON BIRD
         DROPPINGS.

         1.   A weak basic compound that is formed when ammonia
              dissolves in water and that exists only in
              solution.

         2.   Other chemical or common names include Ammonium
              Hydroxide; Aqua ammonia*; Household ammonia*.

         3.   Potential hazards:  TOXIC; MAY IRRITATE THE EYES.

         4.   Available from chemical supply house, grocery store
              or pharmaceutical supply distributor, or hardware
              store.

    C.   Powdered talc

    D.   Plastic sheeting

    E.   Clean, potable water

    F.   Mineral water

2.02 EQUIPMENT

    A.   Glass or ceramic container for mixing the solution

    B.   Wooden utensil for stirring the ingredients

    C.   Wood or plastic spatula

    D.   Stiff bristle brush (non-metallic)


PART 3---EXECUTION

3.01 ERECTION, INSTALLATION, APPLICATION

    A.   Thoroughly rinse the area to be treated with mineral
         water.

    B.   Mix 1 part ammonium chloride or aluminum chloride with 4
         parts powdered talc.

    C.   Add ammonia water and stir to achieve a thick paste.

    D.   Spread the paste over the affected area with a wood or
         plastic spatula to a thickness of about 1/4".

    E.   Cover the area with plastic sheeting and allow to soak
         for three days.

    F.   Remove the plastic and allow the poultice to dry.

    G.   Remove the dried poultice with a wood or plastic spatula
         and a stiff bristle brush.

    H.   Thoroughly rinse the surface with clean, clear water and
         allow to dry.

    I.   Repeat as necessary to achieve the desired level of
         cleanliness.

                         END OF SECTION
 


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