Specification:Removal of copper-based stains from brick, concrete and limestone

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=GENERAL=

SUMMARY
 This procedure includes guidance on removing copper staining on exterior brick, concrete and limestone.  Remove soiling, stains and crusts from the limestone and granite without damaging underlying material and to give all stone a clean, uniform appearance without blotches, streaks or other irregularities. Use the gentlest means to meet the cleaning objective. If the exterior masonry has been previously subjected to inappropriately harsh and uneven cleaning, it is expected that the cleaning will reveal the original colors and textures of the brick, but that it will not completely correct the differential effects of the previous cleaning. Clean brick to remove soiling, stains and crusts to the extent feasible without further damaging the brick.   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</li> Quality Assurance</li> Delivery, Storage and Handling</li> 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= <ol type="A"> Diedrich Chemicals Restoration Technologies, Inc.<= br>         300A East Oak Street Oak Creek, WI  53154 414/764-0058 or 800/323-3565</li> ProSoCo, Inc. 755 Minnesota Avenue P.O. Box 1578 Kansas City, KS 66117 800/255-4255 or 913/281-2700</li> </ol>

MATERIALS
<ol type="A"> Copper-Based Stain Remover: Commercially available, two part poultice cleaning system specifically designed to remove green copper stains from masonry surfaces, such as "Sure Klean T-515 Copper Stain Remover"(ProSoCo, Inc.), or approved equal.</li> Liquid Strippable Masking Agent: Manufacturer's standard liquid, film forming, strippable masking material for protecting glass, metal and polished stone surfaces from damaging effect of acidic and alkaline masonry cleaners, such as "Sure Klean Acid Stop" (ProSoCo, Inc.), "Diedrich Acid Guard" (Diedrich Chemicals), or approved equal.</li> Plastic material for covering poultice</li> Water: Potable, non-staining and free of oils, acids, alkalis and organic matter.</li> </ol>

EQUIPMENT
<ol type="A"> Brushes: Natural fiber bristle only. The use of wire brushes or steel wool is not permitted.<= br> B.   Stainless steel trowel</li> Wood spatula</li> </ol> =EXECUTION=

PREPARATION
<ol type="A"> Protection: Protect from run-off the surfaces below the sections of masonry to be cleaned of copper-based stains using liquid strippable masking agent. B.  Surface Preparation:  Filter water with a 5 micron particulate filter placed in line with the water supply. Replace the filter as needed during the work.</li> <li>Commence copper-based stain removal immediately after cleaning of masonry (see 03710-15-R, 04211- 04-R and 04460-03-R for guidance on the general cleaning of concrete, brick and limestone respectively).</li> <li>The work shall proceed from the top of the wall downward. Work shall not be considered complete until the Contracting Officer of designated representative has so notified the Contractor in writing.</li> </ol> </li> </ol>

ERECTION, INSTALLATION, APPLICATION
<ol type="A"> <li>Prepare the copper-based stain remover by mixing the liquid additive with the dry poultice (Fuller's earth) to a thick cream. Mix thoroughly so that poultice has a smooth, even consistency.</li> <li>Clean dirt or dust from surface being treated prior to application of poultice.</li> <li>Prewet masonry and apply a "AC" thick layer of poultice to the stained surface using a stainless steel trowel or other non-ferrous implement.</li> <li>Cover the poultice with a plastic membrane and allow to dry for 8 to 24 hours depending on test samples.</li> <li>Scrape the poultice from the masonry with a non-metallic implement and scrub with water and a fiber bristle brush.</li> <li>Rinse all traces of chemical residue with pressurized cold water. Rinse water pressure shall not exceed 300 psi, and shall be sprayed through nozzles fitted with 15 to 20 wide tips. Nozzles shall be held perpendicular to the surface at a working distance of 1.5 to 2.5 feet. All pressure pumps shall be equipped with working pressure gauges.</li> <li>Repeat procedure if necessary to remove all traces of copper-based staining.</li> </ol>