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