Specification:Cleaning of atmospheric soiling, biogrowth and mold on historic wood

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=GENERAL=

DESCRIPTION
 This specification provides guidance for the cleaning of atmospheric soiling, biogrowth and mold on historic wood including the removal of soiling, staining, and graffiti. 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. All work described herein and related work must conform to the Secretary of Interior’s Standards for the Treatment of Historic Properties. The Contractor shall provide all labor, materials, 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. The Architect will provide site-specific specifications, when appropriate. 

SECTION INCLUDES
 Historic Exterior Wood: Cleaning of Atmospheric Soiling</li> Historic Exterior Wood: Cleaning of Graffiti</li> Historic Exterior Wood: Cleaning of Biogrowth (Algae & Lichens, Mold & Fungi)</li> </ol>

DEFINITIONS
<ol type="A"> Atmospheric Soiling: The dust, aerosols, and particulate matter deposited from the air directly on the material surface. Particulates can result from vehicle exhaust, sea salts and other contaminants.</li> Biological soiling: Discolorations that include biological growth (biogrowth) and biological deposits. Biogrowth includes microorganisms, including lichens, bacteria, algae, fungi, and molds that discolor the material surface. Factors influencing biogrowth include exposure, orientation, position, and surface texture of the material. Deposited material, such as bird droppings, aphid “honey dew,” and others, are considered biological soiling.</li> Chemical Cleaning: Cleaning methods that involve applying a substance to the material that interacts with the material and any discoloration on the surface. Chemical cleaning methods may include water, organic solvents, and alkaline or acidic chemicals.</li> Cleaning Test Patch: A small unobtrusive area, usually less than 6x6 inch, in which the contractor tests a particular cleaning method. Several cleaning test patches are usually performed side by side to directly compare methods.</li> Complexing and Sequestering agent: an organic chemical that acts to grab and bind metals to itself.</li> Detergent: any chemical substance, other than soap, that is an effective cleanser and functions equally well as a surface-active agent in hard or soft water.</li> Graffiti: Usually an unwanted painting or marking in any manner on property.</li> Laser Cleaning: Uses a coherent light source of specific wavelength and energy to ablate soiling from the surface of a material.</li> Physical Cleaning: Involves the removal of material from the surface using abrasive methods. Physical methods include pressure washing at low and medium pressures, and mechanical or manual brushing.</li> Poultice: In general, this is a cleaning method that involves application of a mixture of a cleaner and an absorbent substance to a surface to draw out contaminants and stains from the surface of a material.</li> Staining: a penetrating discoloration or soiled spot found on the material.</li> </ol>

SUBMITTALS
<ol type="A"> Treatment Schedule: Submit a detailed schedule to the Architect for approval of the areas to be cleaned, 	including an assessment of the problem surfaces, detailed procedure of wood cleaning methods to be used and approved methods for handling of hazardous materials, such as guano.</li> Product Literature: Submit manufacturer’s product literature to the Architect for all proprietary products specified for wood cleaning, removal of graffiti, stain and/or biogrowth removal, guano removal and surface testing. Product literature shall include specification data, Material Safety Data Sheets and instructions for storage, handling and use.</li> Submit test samples or examples of similarly executed wood cleaning to the Architect as required.</li> <li>Submit photographs of the repaired areas taken before, during and after the work upon conclusion of the cleaning.</li> </ol>

QUALITY ASSURANCE
<ol type="A"> <li>The Contractor shall have a minimum of seven years experience in historic wood cleaning and repair. He/She shall have successfully completed at least three wood restoration projects of similar scope within the previous five years. Said work shall be conducted in accordance with the Secretary of Interior’s Standards for the Treatment of Historic Properties.</li> <li>The Contractor shall provide the following warranties for cleaning: <ol> <li>The Contractor is responsible for and assures this agency that hazardous materials and/or products are handled and discarded in accordance with accepted environmentally safe practices. He/She will use perform work in compliance with Occupational Safety & Health Administration (OSHA) regulations and standards.</li> </ol> </li> </ol>

MOCK-UPS
<ol type="A"> <li>The Contractor, at location(s) determined by the Architect, shall prepare cleaning samples, not to exceed 100 square ft. per sample, of the specified products or methods on inconspicuous areas, preferably conducted by the operator undertaking the final work. Allow for proper drying time prior to examination of mock-up.</li> <li>More than one test site and/or sample of product testing may be required to be acceptable for approval. The Contractor shall conduct five such product/surface test samples without further compensation. Approved test area(s) shall become part of the work and shall serve as the quality standard for all similar work.</li> </ol>

DELIVERY, STORAGE AND HANDLING
<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 following manufacturer’s instructions.</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. Work shall not commence when rain, snow or below-freezing temperatures are expected within the next 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. Provide all necessary protection and work procedures to avoid damage to existing material assemblies not a part of the work of this Section.</li> <li>Provide visible barriers and/or warning tape around the perimeter of the work area for visitor protection. Protect nearby vehicles and adjacent structures from damage during the course of the work.</li> <li>The Contractor shall coordinate wood cleaning operations with the other trades involved in exterior and interior restoration work including, but not limited to, masonry restoration, roofing, rough and finish carpentry, sealants, painting, plastering, roof and gutter repairs.</li> <li>The Contractor shall dispose of all packaging, waste and debris in accordance with federal, state and local environmental laws. All wood scrap shall be kept separate for recycling.</li> </ol>

=PRODUCTS=

CLEANING OF ATMOSPHERIC SOILING
<ol type="A"> <li>Investigation and Method Selection <ol> <li>Identification of types of materials, 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.</li> <li>The contractor shall conduct cleaning test patches, usually less than 6x6 inches, in unobtrusive locations on the wood to be cleaned. The purpose of the test patch is to determine the most effective, gentlest method to remove soiling from the wood. Several cleaning methods are generally tested side by side.</li> <li>Under no circumstances is sand blasting to be used to clean historic wood.</li> <li>The method of cleaning and the level of clean shall be approved by the Architect. The Contractor shall protect adjacent materials, installed non wood materials, and openings.</li> </ol> </li> <li>Cleaning Methods: Wood is relatively soft and porous and cannot be treated with the wide variety of chemical solvents that are available for cleaning masonry. Cleaning shall be undertaken through the mildest, least abrasive method that will achieve the desired level of soil removal.</li> <li>Remove atmospheric soiling with solutions made with dilutions of detergents, surfactants, and chelating agents in water. Neutral or non-ionic detergents or surfactants are added to water for use on hydrophobic stains. For more detailed information on solvents see 2.02, CLEANING OF GRAFFITI, below.</li> <li>Equipment for Cleaning: <ol> <li>Pipes and hoses used for water cleaning shall be plastic or other similar material that is not subject to corrosion, which can cause discoloration and staining of surfaces being cleaned.</li> <li>Clean cotton rags or natural bristle brushes shall be used for wiping and scrubbing.</li> <li>Hoses, fittings and equipment to be used for application of proprietary cleaning compounds shall be solvent, acid or alkali-resistant as recommended by the manufacturer of the cleaning products.</li> <li>Rubber gloves.</li> <li>Respiratory mask and protective eyewear.</li> </ol> </li> </ol>

CLEANING OF GRAFFITI
<ol type="A"> <li>Cleaning Methods: Cleaning shall be undertaken through the mildest, least abrasive method.</li> <li>Solvents: Following is a list of solvents and their effectiveness at removal of graffiti. Anything stronger than mineral spirits or turpentine is generally not recommended for cleaning of historic wood as it will damage the paint or transparent finish. Consult project Architect in choosing a solvent that will minimize damage to the wood substrate.

Many chemical removers have the potential to be harmful to workers and to the environment. For information on the environmental impacts of 35 graffiti removal products, see the following report that lists ingredients, and also field tests and rates a dozen products for performance on various surfaces: Stack, Stacey. “Graffiti Remover Research and Field Test Report: The Search for Safer Products”. City of Portland, October 2003. <http://www.newdream.org/procure/Graffiti.pdf> </li> <li>Equipment for Application: See 2.01, CLEANING OF ATMOSPHERIC SOILING, above.</li> <li>Water/Rinsing Method: See 2.01, CLEANING OF ATMOSPHERIC SOILING, above.</li> </ol>

CLEANING OF BIOGROWTH
<ol type="A"> <li>Cleaning Methods: Cleaning shall be undertaken through the mildest, least abrasive method. <ol> <li>Water Washing: Cold water applied by low pressure. Ammonia may be introduced for treatment of algae, fungi, molds, and mildew. Solution for cleaning moldy wood surfaces shall be one cup tri-sodium phosphate (TSP) mixed with two gallons of water.</li> <li>Acidic Cleaners: Formulations of acids, surfactants, and chelating agents.</li> <li>Herbicides: Quaternary ammonium treatment.</li> </ol> </li> <li>Equipment for Application: See 2.01, CLEANING OF ATMOSPHERIC SOILING, above. </li> <li>Water/Rinsing Method: See 2.01, CLEANING OF ATMOSPHERIC SOILING, above.</li> </ol> =EXECUTION=

GENERAL
<ol type="A"> <li>The initial cleaning test patches shall be reviewed by the Architect to determine the mildest cleaning method to be used.</li> <li>The extent of the cleaning (clean level) and areas to be cleaned shall be reviewed by the Architect on site prior to beginning operations. Contractor shall submit testing schedule and a cleaning schedule, including the methods and materials to be used.</li> <li>The Contractor shall protect adjacent materials, installed materials, and openings.</li> <li>Hazardous materials to be handled in accordance with accepted environmental safety procedures.</li> <li>The cleaning runoff will be collected in plywood troughs lined with polyethylene sheeting. Polluted liquid gathered shall be pumped into tanker trucks or drums for properly controlled disposal. Acidic runoff shall be neutralized with lime or soda ash prior to release.</li> </ol>

PREPARATION FOR CLEANING
<ol type="A"> <li>Locate and seal all wall penetrations that might permit water passage to the interior.</li> <li>Window openings shall be protected with waterproof covering during pressure washing operations. No washing shall be performed within six inches of a window opening. These areas, including the window head, jambs and sills shall be scrubbed by hand with plain water and a soft bristle brush.</li> <li>Plastic sheeting shall be placed on a grade from the building line to a point five feet from the building line to direct run-off away from the base of the building.</li> </ol>

CLEANING OF ATMOSPHERIC SOILING
<ol type="A"> <li>Investigations and method selection: Identification of types of materials, surface and substrate conditions, previous treatments, and the nature, cause and pattern of the stain type for each area shall be determined. The method of cleaning and the level of clean shall be approved by the Architect. The Contractor shall protect adjacent materials, including window glass and metal hardware and fixtures.</li> <li>Cleaning methods: Cleaning shall be undertaken through the mildest, least abrasive method. <ol> Cleaning shall be programmed so that dust and other contaminants will not fall on

newly prepared or newly painted surfaces.

<li>Hand washing: Some dirt and soot may be scrubbed off with a medium soft bristle brush</li> using household detergent at a ratio of l/2 cup per gallon of water. Rinse cleaned surface thoroughly and allow wood to dry out before any repainting.

<li>Organic Solvents: See 2.02 CLEANING OF GRAFFITI above.</li> </ol> </li> </ol>

CLEANING OF GRAFFITI
<ol type="A"> <li>Investigations and method selection: Identification of types of materials, surface and substrate</li> conditions, previous treatments, and the nature, cause and pattern of the stain type for each area shall be determined. The method of cleaning and the level of clean shall be approved by the architect. The Contractor shall protect adjacent materials, installed non concrete materials, and openings.

<li>Cleaning methods: Cleaning shall be undertaken through the mildest, least abrasive method. <ol>Cleaning shall be programmed so that dust and other contaminants will not fall on newly prepared or newly painted surfaces. Cleaning methods for graffiti include solvents, pressure washing, sanding, and repainting.

<li>Solvents: <li>Choosing the right solvent is critical, as using the wrong one can damage building materials, tools or both. The longer the graffiti has to dry, the stronger the solvent and more difficult the cleaning process will be. The Contractor should be familiar with the most useful solvents and where, when and how to use them. In general, solvents stronger than mineral spirits are generally not recommended for use on historic wood. It is also important to note that if wood is excessively weathered, solvents may be absorbed by the wood, driving the paint further down into the material.</li> <li>Beginning with the weakest solvent, work down the list (see 2.02, PRODUCTS – CLEANING GRAFFITI, above) depending on the severity of the damage and the substance used. Most paint thinners such as mineral spirits, turpentine and naphtha will remove magic markers, and acetone will remove day old spray paint.</li> <li>Gently scrub surface using a clean, low-nap rag. Use clean part of rag with each wipe to avoid smearing graffiti as it softens.</li> </ol> </li> <li>Sanding: If neither gentle solvents such as mineral spirits nor washing work, the wood can be sanded down to remove the graffiti and then refinished. Alternatively, the graffiti can simply be painted over. Painting over a surface that already has several coats of paint may require using a scraper and sanding to properly prepare if for a new coat of paint. Consider applying a protective coating after two or three paint-outs to prevent the need for repainting.</li> </ol> </li> </ol>

CLEANING OF BIOGROWTH
<ol type="A"> <li>Investigations and method selection: Identification of types of materials, surface and substrate conditions, previous treatments, and the nature, cause and pattern of the stain type for each area shall be determined. The method of cleaning and the level of clean shall be approved by the Architect. The Contractor shall protect adjacent materials and openings. If applicable reference ASTM D 3274, Evaluating Degree of Surface Disfigurement of Paint Films by Microbial (Fungal or Algal) Growth or Soil and Dirt Accumulation.</li> <li>Cleaning methods: Cleaning shall be undertaken through the mildest, least abrasive method. <ol> Cleaning shall be programmed so that dust and other contaminants will not fall on newly prepared or newly painted surfaces.

<li>General Cleaning <li>Remove loose growth from wood surfaces with non-marring scrapers.</li> <li>Apply selected cleaning agent in accordance with manufacturer’s instructions an b. approved test panel. Allow product to dwell on soiled surfaces to achieve optimal cleaning.</li> <li>After completion of required dwell time, agitate with a bristle brush to lift and remove embedded growth. Flush surfaces with low to moderate pressure (up to 700 psi) water rinse as required to remove staining.</li> </ol> </li> <li>Cleaning Methods - Algae and Lichens: Dirt and surface contaminants shall be cleaned by brush with solutions of water and detergent or trisodium phosphate, then rinsed clean with water and let dry. Oil and grease shall be removed with clean cloths and cleaning solvents prior to mechanical cleaning.</li> <li>Cleaning Methods - Mildew <li>Cause: Mildew is caused by fungi feeding on nutrients contained in the paint film or on dirt adhering to any surface. Because moisture is the single most important factor in its growth, mildew tends to thrive in areas where dampness and lack of sunshine are problems such as window sills, under eaves, around gutters and downspouts, on the north side of buildings, or in shaded areas near shrubbery.</li> <li>Test to distinguish mildew from dirt: if a drop of household bleach is placed on b.	the suspected surface, mildew will immediately turn white while the appearance of dirt will remain unchanged.</li> <li>Treatments for surfaces on which mildew or other microbiological growth is c.	present: Using medium soft brush, clean with detergent solution containing two cups non-ammoniated detergent, and one gallon water. Add up to an additional quart of bleach for heavily affected areas. After mildew is removed, rinse with a direct stream of water allow to dry thoroughly. When repainting, specially formulated "mildew-resistant" primer and finish coats should be used.</li> </ol> </li> </ol> </li> </ol>

FINAL REPORT
<ol type="A"> <li>Provide a final report of complete work including all approved submittals and photographs of the repaired areas taken before, during and after the work.</li> </ol>