Specification:Masonry poulticing and salt removal

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=GENERAL=

DESCRIPTION
 This specification provides guidance for cleaning historic masonry materials, including the removal of soiling, staining, graffiti, and biogrowth. This specification has been developed for use on historic properties (defined as any district, site, building, structure, or object that is listed in or eligible for listing in the National Register of Historic Places) and provides an overview of accepted practices. The Architect will provide site-specific specifications, when appropriate. All work described herein and related work must conform to the Secretary of the Interior’s Standards for the Treatment of Historic Properties. The Contractor shall provide all labor, material, equipment, and operations required to complete the rehabilitation work indicated herein. All work described herein and related work must have the approval of a Cultural Resources Manager, Conservator, Historic Architect, or other professional who meets the standards outlined in the Secretary of the Interior’s Standards – Professional Qualifications Standards pursuant to 36 CFR 61. Such person is referred to in this document as the Architect. 

SECTION INCLUDES
 Masonry poulticing with paper- and clay-based poultices. Masonry removal of salts with surfactants and water based treatment.</li> </ol>

RELATED SECTIONS
<ol type="A"> Specification:Concrete cleaning: removal of atmospheric soiling, staining, graffiti, and biogrowth</li> Specification:Removal of mortar joints and repointing</li> Specification:Preparation of lime- or Portland-based stucco</li> Specification:Repair of historic stucco</li> Specification:Historic brick properties and in-kind replacement</li> Specification:Brick repair through patching</li> Specification:Terra-cotta patching and glaze repair</li> Specification:Masonry cleaning: removal of atmospheric soiling, graffiti, stains, and biogrowth</li> </ol>

SUBMITTALS
The Contractor shall submit to the Architect for approval: <ol type="A"> A detailed schedule of the areas to be cleaned, including an assessment of the problem surfaces, proposed masonry procedures, application methods, dwell times, etc., once cleaning test panels are completed and approved.</li> Manufacturer’s product literature for all proprietary cleaning products. Product literature shall include specification data, Material Safety Data Sheets and instructions for storage, handling, and use.</li> </ol>

QUALITY ASSURANCE
<ol type="A"> The Contractor to perform the work of this Section shall have a minimum of seven years experience in historic masonry cleaning and shall have successfully completed at least three projects of similar scope within the previous five years. </li> The Contractor shall demonstrate with project descriptions, photographs and references successful experience in all specified cleaning techniques. </li> Contractor experience shall include cleaning exterior masonry stains of similar type, complexity, and similar materials. He/She shall demonstrate a working knowledge of The Secretary of the Interior’s Standards for the Treatment of Historic Properties with Guidelines for Preserving, Rehabilitating, Restoring & Reconstructing Historic Buildings. </li> </ol>

MOCK-UPS
<ol type="A"> The Contractor, at locations designated by the Architect, shall prepare test panels, not to exceed 100 square feet per sample, demonstrating the cleaning product(s) on inconspicuous areas, preferably conducted by the operator undertaking the final work. The Contractor shall prepare test panels of each method utilized under this section:  Poultice Cleaning for Desalination. A minimum of one square foot for each type of masonry unit and each product to be used.</li> <li>Poultice Cleaning for Iron and Copper Stains. Two areas, a minimum of one square foot at each test panel for each type of masonry unit and each specified product.</li> <li>Poultice Cleaning for Paint Remover and Tar/Mastic Remover. Approximately ten square feet for each type of masonry/stone unit and each procedure to be performed.</li> <li>Poultice Cleaning for Oil and/or Grease Stains. A minimum of one square foot for each type of masonry unit and each product to be used.</li> </ol> </li> <li>Preparation of the cleaning sample panels shall be used to determine the appropriate concentrations and dwell times for the remainder of the cleaning work. Following approval of the cleaning test panels, the Contractor shall submit the approved procedures in writing to the Architect.</li> <li>Preparation of test panels shall begin with the lowest concentration of cleaner and the shortest dwell time recommended by the manufacturer. Concentration and/or dwell time shall be increased as required up to the maximum recommended by the product manufacturer.</li> <li>More than one test panel may be required to be acceptable for approval. The Contractor shall prepare at least four test panels of each type, if necessary, without further compensation. Approved test panels shall become part of the work and shall serve as the quality standard for all similar work.</li> </ol>

DELIVERY, STORAGE, AND HANDLING
The Contractor shall: <ol type="A"> <li>Deliver restoration cleaning and testing materials and proprietary products to the project site in manufacturer’s or distributor’s packaging, undamaged, complete with application instructions and Material Safety Data Sheets.</li> <li>Store and transport cleaning agents, chemicals and solvents within the temperature range recommended by the manufacturer and away from direct sunlight. Handle all materials according to manufacturer’s instructions.</li> <li>Collect and dispose of waste material, packaging, debris, and effluent associated with the masonry cleaning work in accordance with local, state and federal environmental regulations.</li> <li>The Contractor shall follow manufacturer instructions for the handling of all materials, and remove all solvents, soiled rags, applicators and other flammable materials daily and dispose of these materials off-site according to local, state and federal regulations.</li> </ol>

PROJECT/SITE CONDITIONS
<ol type="A"> <li>The work of this Section shall be executed only when the air and surface temperatures are 40 degrees F and rising or less than 90 degrees F and falling. Minimum temperature for masonry cleaning shall be 50 degrees F and above for at least two hours after completion and above freezing for at least 24 hours after completion. Work shall not commence when rain, snow or below-freezing temperatures are expected within 24 hours. All surfaces shall be free of standing water, frost and ice.</li> <li>The Contractor is responsible for protecting existing adjacent materials during the execution of the work and shall provide necessary protection and follow all work procedures to prevent damage to existing material assemblies not a part of the work of this Section. At a minimum, the Contractor shall: <ol> <li>Protect woodwork, glass and metal adjacent to masonry areas to be cleaned from possible chemical or water damage from cleaning operations. Cover all window openings with waterproof plastic to prevent leakage to the building interior.</li> <li>Protect surrounding lawns and vegetation from runoff during rinsing operations.</li> <li>Access work areas from the exterior only. Under no circumstances are hoses to be run or equipment to be transported through the building during cleaning operations.</li> </ol> </li> <li>The Contractor shall erect enclosures around areas where poulticing operations are in progress to protect passers-by from contact with cleaning chemicals or rinse water.</li> <li>Contractor shall coordinate masonry cleaning operations with the other trades involved in exterior and interior restoration work, including but not limited to masonry restoration, sealing and painting. Complete masonry cleaning prior to restoration of windows, doors and metalwork and prior to any exterior painting in the affected areas.</li> <li>All Contractor personnel performing masonry cleaning operations shall be provided with gloves, respirators and protective clothing as recommended by the manufacturer of the masonry cleaning products.</li> <li>The Contractor shall complete installation of temporary sealants at window and door perimeters prior to starting cleaning operations where required to prevent leakage to interior.</li> </ol> =PRODUCTS=

GENERAL
<ol type="A"> <li>The type of stone to be cleaned must be identified. Identification of surface and substrate conditions, previous treatments, and the nature, cause and pattern of the soiling type for each area shall be determined. Testing may require additional technical expertise from a materials scientist, architectural conservator, microbiologist and/or other technical expert. The Contractor shall choose the gentlest method possible to remove the soiling without damaging the substrate material. The method of soil removal must be compatible with the stone type and type of soiling.</li> <li>Cleaning and rinse water shall be potable and free of injurious amounts of oil, soluble salts, alkali, acids and other impurities that might stain or otherwise damage masonry.</li> </ol>

EQUIPMENT
<ol type="A"> <li>Clean pail or containers for preparation of poultices</li> <li>Nonmetallic spatulas</li> <li>Wooden scrapers</li> <li>Trowels</li> <li>Natural and synthetic fiber bristle brushes</li> <li>Polyethylene sheeting</li> <li>Protective paper recommended by the manufacturer</li> <li>Japanese tissue or thin polyester geotextile, 200 g/sq m (for use on very porous or highly textured masonry surfaces)</li> </ol>

MATERIALS AND MANUFACTURERS
<ol type="A"> <li>Cleaning materials including poultice clay, poultices for iron and copper staining; poultices for oil and grease removal, remover for paint adhesives, asphalt, sealant and tar shall be products appropriate for the work in this section and manufactured by industry-recognized sources. The Contractor shall submit all selected materials and manufacturers to the Architect for approval.</li> </ol>

ACCESSORIES AND RELATED MATERIALS
<ol type="A"> <li>Temporary Sealant: Non-staining, removable sealant suitable for masonry substrates.</li> <li>Brushes for scrubbing masonry and stucco shall be stiff-bristle, nonmetallic brushes as recommended by the manufacturer of the masonry cleaning products. Metal bristle brushes shall NOT be used.</li> </ol> =EXECUTION=

GENERAL
<ol type="A"> <li>The extent of the cleaning (desired level of cleaning) and areas to be cleaned shall be reviewed by the Architect on site prior to beginning operations. The Contractor shall submit testing schedule and a cleaning schedule, including the methods and materials to be used.</li> <li>Masonry cleaning is to be completed prior to masonry repointing and repairs. The Contractor shall remove and store light fixtures, downspouts, and other appurtenances to ensure full access to wall surfaces, unless otherwise noted by the Architect. Anchor holes and penetrations from appurtenances must be temporarily filled with removable sealant or protected with cover plates.</li> <li>The Contractor shall protect all adjacent materials from rinse water and poultice chemicals.</li> <li>The cleaning/rinsing runoff shall be collected by wet vacuum or in plywood troughs lined with polyethylene sheeting. Polluted liquid shall be gathered and stored in plastic containers for properly controlled disposal. Acidic runoff shall be neutralized with lime or soda ash prior to release.</li> <li>Masonry cleaning shall employ the gentlest means possible. When evidence of deterioration causes doubts about the ability of a stone or other masonry unit to withstand rinsing pressures and manual scrubbing or scraping, remove cleaning products as gently as possible and cease the cleaning procedure at that location. The Contractor shall notify the Architect of the location and condition of masonry units involved.</li> </ol>

SURFACE PREPARATION FOR CLEANING
<ol type="A"> <li>The Contractor shall examine the surfaces to be cleaned prior to commencing cleaning operations. Large cracks (1/8 inch or larger) and open joints discovered in the area to be cleaned shall be temporarily filled with removable sealant to prevent penetration of cleaning materials.</li> <li>Window and door opening shall be protected from leakage and damage from cleaning materials and spray by plastic sheeting or other waterproof membrane. Open joints around window frames and door frames shall be filled with temporary sealant to prevent leakage.</li> <li>The Contractor shall remove all invasive vegetation and plant debris prior to cleaning. With the approval of the Architect, invasive vines shall be cut close to the ground and allowed to wither and dry. The dry vines shall be carefully removed and the façade surface cleaned with a natural bristle brush prior to other treatments.</li> </ol>

POULTICING WITH CLAY OR PAPER BASED POULTICES
<ol type="A"> <li>Dampen the surface area to be cleaned with clean water.</li> <li>In a plastic bucket or container, combine poultice ingredients in accordance with manufacturer’s printed instructions. Stir continuously until the mixture forms a smooth, wet paste.</li> <li>Apply a layer of poultice paste, 1/8 inch to 1/4 inch in thickness, immediately to the stained surface. Surfaces to be cleaned should be free of surface dirt or dust.</li> <li>Leave poultice paste on the masonry surface until completely dry or for a maximum of 24 hours.</li> <li>During hot and/or windy conditions or to protect passersby, the Contractor shall cover poultice with protective paper covering, sealing and taping the edges. Leave covered for 12-24 hours, adjusting dwell time for cases of extreme humidity. Remove covering, and if the poultice is still wet, allow it to dry completely.</li> <li>Once the poultice is completely dried, the Contractor shall scrape mixture from the surface using wood, plastic, or rubber spatulas.</li> <li>Rinse the treated area thoroughly with water and use a soft brush to remove remaining residue.</li> <li>Reapply poultice for consecutive treatments if required.</li> </ol>

SALT REMOVAL WITH SURFACTANTS AND WATER BASED TREATMENTS
<ol type="A"> <li>In a plastic bucket or container, combine poultice filler (paper fiber or clay) ingredients with water. Stir continuously until the mixture forms a smooth, wet paste.</li> <li>Apply a layer of poultice paste 1/8 inch to 1/4 inch in thickness immediately to the stained surface. Surfaces to be cleaned should be dry and free of surface dirt or dust.</li> <li>Leave poultice paste on the masonry surface until completely dry or for a maximum of 24 hours.</li> <li>Once the poultice is completely dried, scrape mixture from the surface using wood, plastic, or rubber spatulas.</li> <li>Rinse the treated area thoroughly with water and use a soft brush to remove remaining residue.</li> <li>After each application, the Contractor shall test poultice material after it is removed to determine the salt concentration and the need for additional treatments. The Contractor shall reapply poultice for consecutive treatments, as needed. When cleaning limestone, the Contractor shall check between each application to ensure that the removal of the salts is not causing discoloration of the stone.</li> </ol>

REMOVAL OF METALLIC STAINS
<ol type="A"> <li>In a plastic bucket or container, combine poultice ingredients in accordance with manufacturer’s printed instructions. Stir continuously until the mixture forms a smooth, wet paste.</li> <li>Apply a layer of poultice paste, 1/8 inch to 1/4 inch in thickness, immediately to the stained surface. Surfaces to be cleaned should be dry and free of surface dirt and dust.</li> <li>Leave poultice paste on masonry until completely dry, or for a maximum of 24 hours.</li> <li>Once the poultice is completely dried, the Contractor shall scrape mixture form the surface using wood, plastic, or rubber spatulas. Rinse the treated area thoroughly with water and use a soft brush to remove remaining residue.</li> </ol>

REMOVAL OF OIL AND GREASE
<ol type="A"> <li>Mix poultice ingredients thoroughly and apply a coat to completely cover the stained area, following manufacturer’s instructions. Do not pre-wet the surface.</li> <li>Allow poultice to dry for five to eight hours overnight until completely dried. Fully developed cracking indicates that the poultice is completely dry.</li> <li>Protect poultice from pedestrian contact and rain while drying. Area may be tented with plastic. Do NOT use tightly-adhered covers.</li> <li>The Contractor shall remove residue powder and properly dispose of the residue. Low pressure water rinsing can be used on textured finished to facilitate removal of the poultice residue.</li> </ol>

PAINT REMOVAL
<ol type="A"> <li>Scrape loose material from surface to the greatest extent possible.</li> <li>Prepare poultice-solvent mixture in accordance with manufacturer’s instruction.</li> <li>Apply the poultice to the stained area to a minimum thickness of 1/4 inch.</li> <li>The poultice shall be covered with a plastic film to prevent drying. Press the film to the poultice, and tape and seal edges. Allow the poultice to dwell on the surface in accordance with the approved test panel.</li> <li>After dwell time, remove the plastic cover.</li> <li>Remove the poultice and softened residue by scraping with a nonmetallic spatula. Wash the surface thoroughly with fresh water. Scrub with a stiff bristle brush to loosen spots. Do not allow poultice material to dry on surface.</li> <li>The process shall be repeated as needed.</li> </ol>

SEALANT, TAR AND MASTIC REMOVAL
<ol type="A"> <li>The Contractor shall clean bituminous material from surfaces of walls using wood scrapers to remove bulk of material prior to applying specified remover.</li> <li>Masonry shall be cleaned using specified cleaning agent in accordance with manufacturer’s instructions. The Contractor shall: <ol> <li>Pre-wet the surface with clean water.</li> <li>Thoroughly rinse the surface after cleaning and apply neutralizing agent if required by manufacturer.</li> <li>Keep area below the stain wet and rinsed free of cleaning residues.</li> <li>Remove protective coverings from adjacent surfaces and repair any damage or staining caused by the cleaning operation to adjacent surfaces.</li> </ol> </li> </ol>

MARBLE CLEANING
<ol type="A"> <li>In a container, mix the ingredients according to manufacturer’s instructions until a dry paste is formed. Gradually add water until troweling consistency is reached.</li> <li>Apply the poultice to the surface to provide an even covering of 1/4 inch.</li> <li>Cover the poultice with protective sheets as recommended by manufacturer. Rub to remove air pockets and ensure smooth adhesion, then tape and seal edges.</li> <li>Leave the poultice covered for 12 to 24 hours; adjust dwell time in extreme humidity.</li> <li>Remove the film. If the film is still wet, allow the poultice to dry for an additional two to four hours.</li> <li>Remove the poultice and dissolved staining matter by inserting a non-metallic scraper, spatula, or other tool through the paste and lifting from the surface. Remove as much residue as possible.</li> <li>Wash the surface thoroughly with fresh water using a sponge, soft brush, or cloth and allow surface dry thoroughly.</li> <li>Repeat the process as needed.</li> </ol>

FINAL REPORT
The Contractor shall: <ol type="A"> <li>Provide a final report of complete work including all approved submittals and photographs of the areas cleaned taken before, during, and after the work.</li> <li>Provide a written summary of the project and results upon final inspection and approval. The summary shall include a discussion of steps taken or new findings not specified in the initial documentation.</li> </ol>