Specification:Poulticing copper/bronze stains from brick masonry

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=GENERAL=

SUMMARY
 This procedure includes guidance on removing copper/bronze stains from brick masonry. See 01100-07-S for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections:  Safety Precautions Historic Structures Precautions Submittals Quality Assurance Delivery, Storage and Handling Project/Site Conditions</li> Sequencing and Scheduling</li> General Protection (Surface and Surrounding)</li> </ol> </li> </ol> 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). =PRODUCTS=

MATERIALS
<ol type="A">

Ammonium Chloride - salt-like substance (NH4Cl): <ol> A white crystalline volatile salt that is used in dry cells and as an expectorant.:</li> Other chemical or common names include Ammonium hydrochloride; Chloride of Ammonia*; Hydrochloride of Ammonia*; Muriate of Ammonia*; Sal Ammoniac*.</li> Potential hazards: TOXIC; CORROSIVE TO FLESH; CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS.</li> Available from chemical supply house, dry cleaning supply distributor, drugstore or pharmaceutical supply distributor, or hardware store.</li> </ol> </li> -OR- Aluminum Chloride: Available from chemical supply house, drugstore or pharmaceutical supply distributor. Ammonia water: <ol>

A weak basic compound that is formed when ammonia dissolves in water and that exists only in solution.</li> Other chemical or common names include Ammonium Hydroxide; Aqua ammonia*; Household ammonia*.</li> Potential hazards: TOXIC; MAY IRRITATE THE EYES.</li> Available from chemical supply house, grocery store or pharmaceutical supply distributor, or hardware store.</li> </ol> </li> Powdered talc</li> Plastic sheeting</li> Clean, potable water</li> Mineral water</li> </ol>

EQUIPMENT
<ol type="A"> <li>Glass or ceramic container for mixing the solution</li> <li>Wooden utensil for stirring the ingredients</li> <li>Wood or plastic spatula</li> <li>Stiff bristle brush (non-metallic)</li> </ol> =EXECUTION=

ERECTION, INSTALLATION, APPLICATION
<ol type="A"> <li>Thoroughly rinse the area to be treated with mineral water.</li> <li>Mix 1 part ammonium chloride or aluminum chloride with 4 parts powdered talc.</li> <li>Add ammonia water and stir to achieve a thick paste.</li> <li>Spread the paste over the affected area with a wood or plastic spatula to a thickness of about 1/4".</li>   <li>Cover the area with plastic sheeting and allow to soak for three days.</li>    <li>Remove the plastic and allow the poultice to dry.</li>    <li>Remove the dried poultice with a wood or plastic spatula and a stiff bristle brush.</li>    <li>Thoroughly rinse the surface with clean, clear water and allow to dry.</li>    <li>Repeat as necessary to achieve the desired level of cleanliness.</li>  </ol>