Specification:General cleaning of metal

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=GENERAL=

DESCRIPTION
 This specification provides guidance for general cleaning of metal. 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
 Metal Cleaning of Atmospheric Soiling, Staining and Corrosion 

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. The Contractor shall submit proposed metal cleaning procedures, application methods, dwell times, etc., once cleaning test panels are completed and approved.</li> Product Literature: Submit manufacturer product literature to architect for all proprietary metal cleaning products. Product literature shall include specification data, Material Safety Data Sheets and instructions for storage, handling, and use.</li> Examples: Submit examples of similarly executed finished projects on the appropriate type of metal.</li> </ol>

QUALITY ASSURANCE
<ol type="A"> The Contractor performing the work of this Section shall have a minimum of seven years experience in historic metal cleaning and restoration and have successfully completed at least three projects of similar scope within the previous five years. The Contractor shall also demonstrate a working knowledge of the Secretary of the Interior's Standards for the Treatment of Historic Properties with Guidelines for Preserving, Rehabilitating, Restoring and Reconstructing Historic Buildings.</li> The Contractor shall provide the warranties for cleaning: the Contractor is responsible for seeing that hazardous materials and/or products are handled and discarded in accordance with accepted environmental safety practices, and he/she will perform the work in compliance with Occupational Safety & Health Administration (OSHA) regulations and standards.</li> </ol>

MOCK-UPS
<ol type="A"> The Architect shall designate where the contractor is to prepare test panels of each cleaning product or process. The area shall not exceed 100 square feet per sample. Mock-ups shall be prepared by the operator(s) undertaking the final work.  Water Soak Cleaning – Approximately 100 square feet.</li> Chemical Cleaners – Approximately 50 square feet for each specified product.</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 as specified in Paragraph 1.04.A. Test panels shall begin with the lowest concentration of cleaner and the shortest dwell time recommended by the manufacturer, and proceed to stronger concentrations with longer dwell times.</li> </ol> </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
<ol type="A"> Deliver all materials and proprietary products to the project site in original packaging along with application instructions and Material Safety Data Sheets.</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> Collect and dispose of waste material, packaging, debris, and effluent associated with the metal cleaning workin accordance with local, state, and federal environmental regulations.</li> </ol>

PROJECT / SITE CONDITIONS
<ol type="A"> The Contractor will not execute  any work in this Section  when the air and surface temperatures are outside the operating range of 40 degrees F and rising or less than 90 degrees F and falling. Do not work when rain, snow, or below-freezing temperatures are expected within 24 hours.</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. At a minimum, the Contractor shall: <ol> <li>Protect woodwork, glass, and masonry adjacent to metal areas to be cleaned from overspray and 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 cleaning operations.</li> <li>Allow access to work areas from the exterior only. Under no circumstances are hoses to be run through or equipment to be transported through the building during cleaning operations.</li> </ol> </li> <li>The Contractor shall erect waterproof enclosures around areas where cleaning operations are in progress to protect nearby property and passers-by from overspray of cleaning chemicals or rinse water.</li> <li>The Contractor shall coordinate metal cleaning operations with the other trades involved in exterior and interior restoration work including, but not limited to, masonry restoration, sealants, and painting. Complete metal cleaning prior to restoration of windows, doors, and masonry and prior to any exterior painting in the affected areas.</li> <li>The Contractor personnel performing metal cleaning operations shall be provided with gloves, respirators, and protective clothing as recommended by the manufacturer of the cleaning products.</li> <li>Compete installation of temporary sealants at window and door perimeters prior to starting cleaning operations where required to prevent leakage into interior.</li> </ol> =PRODUCTS=

CLEANING OF ATMOSPHERIC SOILING, STAINING, AND CORROSION
<ol type="A"> <li>General: This section is intended to address the basic materials and equipment needed for the cleaning of surface dirt, debris, atmospheric soiling, or discoloration on the more common architectural metals. More advanced levels of deterioration such as severe staining or corrosion should be addressed following the removal of atmospheric soiling, dirt buildup, and biological growth.</li> <li>Investigation and method selection: Determine the type of metal, conditions of surface and substrate, previous treatments and stain type by nature, cause, and pattern for each area. The Architect shall approve the method of cleaning and the optimal level of cleaning.</li> <li>Cleaning methods: Cleaning shall be undertaken through the mildest, least abrasive method. <ol> <li>Water washing: Wash the surface with low to medium jet pressure, 200-1000 psi at 4-6 gpm using a 45 degree fan type nozzle for water soluble dirt and chemical compounds. Optimal water pressure should be determined during preparation of cleaning samples.</li> <li>Nebulous Sprays: Apply intermittent mist spray under low pressure to dampen surface. Remove dirt by scrubbing and agitation.</li> <li>Detergents: Make formulations with dilutions of detergents, surfactants, and chelating agents in water. Add neutral or non-ionic detergents or surfactants to water for use on hydrophobic stains.</li> <li>Metal Cleaners: If this type of product is proposed, exercise great care in product selection and preparation of test panels to identify potentially detrimental effects on the metal and surrounding materials.</li> </ol> </li> </ol>

CLEANING ALUMINUM
<ol type="A"> <li>Materials <ol> <li>Aluminum Cleaners <li>Mild Soaps, Non-Ionic, and Non-etching Detergents: Spot test detergents prior to use as some may discolor non-finished and anodized aluminum or bleach painted aluminum.</li> <li>Solvent and Emulsion Cleaners: These can be used on bare, anodized, conversion coatings, and porcelain-finished aluminum. Spot tests should be tried first on inconspicuous areas and product directions should always be followed.</li> <li>Abrasive Cleaners: Abrasive cleaners are moderate and heavy-duty cleaners including polishes, cleaners, cleaner-polishes, wax cleaners, scouring powders, and metal brighteners containing abrasive particles. They may also include water, oil, wax, silicones, soap, acids, or alkalis. Abrasive cleaners also include etching cleaners and special heavy-duty cleaners. <li>These cleaners depend on vigorous rubbing action along with a chemical reaction, and can remove most dirt, stains, and corrosion products from aluminum and will restore most weathered aluminum surfaces.</li> <li>Only use household cleaners with coarse abrasives on aluminum with porcelain finishes. Using fine pumice powder, synthetic fiber scouring pads, and stainless steel wool (grades 0000 to 00) is permitted with these cleaners, but regular steel wool may leave rust stains.</li> </ol> </li> <li>Etching Cleaners.</li> <li>Special Duty Cleaners: Special duty cleaners will remove aluminum oxidation, atmospheric dirt and carbon, and other surface stains from all types of aluminum surfaces.</li> </ol> </li> <li>Acrylate emulsion polish.</li> <li>Water: Cleaning water shall be potable, free of injurious amounts of oil, soluble salts, alkalis, acids, and other impurities that might stain or otherwise damage historic metals.</li> </ol> </li> <li>Equipment <ol> <li>Nylon bristle brushes</li> <li>Light-weight scrubbing machine with nylon pads</li> <li>Cellulose sponge mop or similar applicator</li> <li>Heavy gloves and protective gear</li> <li>Water hose and nozzle</li> </ol> </li> </ol>

CLEANING COPPER
<ol type="A"> <li>Materials <ol> <li>Copper Sulfate: A sulfate of copper is white in the anhydrous form and blue in the crystalline hydrous form; it is often used as an algicide and fungicide. Chemical or common names include Cupric Sulfate, Blue stone, Blue vitriol, or Roman vitriol. (NOTE: Toxic)</li> <li>Nitric Acid: Nitric acid is a corrosive liquid inorganic acid used especially as an oxidizing agent, in nitrations, and in making organic compounds such as fertilizers, explosives, and dyes. It is corrosive to flesh, concrete, steel, wood, and glass.</li> <li>Water: Cleaning water shall be potable, free of injurious amounts of oil, soluble salts, alkalis, acids, and other impurities that might stain or otherwise damage historic metals.</li> </ol> </li> <li>Equipment <ol> <li>Cellulose sponge mop or similar applicator.</li> <li>Clean, soft, lint-free wiping cloths.</li> <li>Heavy gloves and protective gear.</li> <li>Water hose.</li> </ol> </li> </ol>

CLEANING BRASS AND BRONZE
<ol type="A"> <li>Materials <ol> <li>Neutral detergent / conservation-approved soap.</li> <li>Mineral Spirits: Other chemical or common names include Benzine, Naphtha, Petroleum spirits, or Solvent naphtha. (NOTE: Toxic)</li> <li>Trisodium phosphate (TSP) or sudsy ammonia, properly diluted in clean, clear water: TSP is banned in some states such as California. Request regulatory information as well as alternative or equivalent chemicals from the Environmental Protection Agency (EPA) regional office and/or the state office of environmental quality.</li> <li>Sodium Hexametaphosphate.</li> <li>Corrosion Inhibitor, Benzotriazole (BTA).</li> <li>Water.</li> </ol> </li> <li>Equipment <ol> <li>Clean, soft, lint-free wiping cloths.</li> <li>Soft natural bristle brushes (non-metallic).</li> <li>Wooden scrapers.</li> <li>Fine bronze wool or silicon carbide abrasive pads, or standard commercially available pumice stone or stainless steel wool. Do NOT use non-stainless steel wool as it may promote discoloration.</li> <li>Rubber gloves.</li> <li>Eye and skin protection.</li> <li>Air-abrasive cleaning equipment (80-100 psi) for use with fine grit dry and wet abrasives. Consult the supervising Architect.</li> <li>Water hose.</li> </ol> </li> </ol>

CLEANING FERROUS METALS (Steel, Wrought and Cast Iron)
<ol type="A"> <li>Materials <ol> <li>Detergent: Non-ionic, controlled sudsing, silicate buffered, rinseless-type synthetic detergent containing no soap, free alkalis, solvents, abrasives, acids, caustics, or the like.</li> <li>Complexing agent: such as EDTA or approved equal.</li> <li>Water: Cleaning water shall be potable, free of injurious amounts of oil, soluble salts, alkalis, acids, and other impurities that might stain or otherwise damage historic metals.</li> </ol> </li> <li>Equipment <ol> <li>600 grit aluminum oxide paper, emery paper, or fine steel wool.</li> <li>Toweling or rags, clean, lint-free.</li> <li>Buckets, molded rubber or plastic: 12 or 14 quart size.</li> <li>Washing brushes: Available from local janitorial supply houses or hardware stores. <li>Tampico fiber set in a hardwood block.</li> <li>Whitewash brush: ideal for most purposes.</li> <li>Parts washing brush: useful for small areas and crevices.</li> </ol> </li> <li>Rubber gloves and rain gear, if desired.</li> <li>Water hose.</li> <li>For light surface rust: <li>Emery paper.</li> <li>Sandpaper, 600 grit aluminum oxide.</li> <li>Fine steel wool.</li> </ol> </li> <li>For medium surface rust. <li>Putty knife.</li> <li>Fine stainless steel wire brush (to removes rust, flaking metal and loosened paint).</li> <li>Scrapers.</li> </ol> </li> <li>For heavy rust, a coarse to medium grits of open-coat aluminum oxide or flint sandpaper or emery paper.</li> </ol> </li> </ol> =EXECUTION=

GENERAL
In cleaning metals, use the gentlest methods first. Only use more aggressive methods if the milder methods are not effective. Using abrasive methods when not necessary may lead to permanent damage, necessitating the replacement of an entire object or section of metal.

SYSTEM FOR CLEANING ATMOSPHERIC SOILING, STAINING AND CORROSION
<ol type="A"> <li>General Method for Cleaning by Mild Water Washing All Metals (with or without detergents, using soft natural bristle brushes): <ol> <li>Water washing alone will remove most common dirt and grime, though supplemental materials may be needed to remove more stubborn deposits.</li> <li>Fill one or two buckets with about two gallons of water. <li>For bronze: Add corrosion inhibitor (BTA) to wash water to make a one to three percent solution of BTA to water.</li> <li>For detergent washing: Add one to three ounces of detergent (see PART 2 – PRODUCTS, above, for each metal type) per gallon of water.</li> </ol> </li> <li>Beginning at the top and gradually working down, scrub the metal surface lightly with the fiber brush to remove any superficial deposits. Take care to avoid scratching or otherwise damaging the metal surface.</li> <li>Rinse surfaces with water after cleaning. Collect and dispose of rinse water as stipulated. Rates of water pressure shall be 200-300 psi at 3-6 gpm with minimal saturation. For cast iron, rinse with two percent aqueous solution of EDTA or approved equal.</li> <li>Dry with clean, lint-free toweling or rags.</li> <li>For tenacious mineral deposits or exudations of core material, treat locally with gentle abrasion using very fine bronze wool, stainless steel wool, or synthetic cleaning pad as appropriate to metal type and surface conditions. Exercise care to avoid damage to surface.</li> </ol> </li> <li>Removing Dirt Build-Up With Chemical Cleaners – All Metals <ol> <li>Preparation <li>Comply with recommendations of manufacturers of chemical cleaners and paint removers for protecting building surfaces from exposure to their products.</li> <li>Protect glass, metal trim and polished stone from contact with acidic or alkali chemical cleaners by covering them with liquid strippable masking agent or polyethylene film and waterproof masking tape. Apply masking agent to comply with manufacturer's recommendations. Do not apply liquid masking agent to adjacent painted or porous surfaces; use waterproof masking tape.</li> <li>Remove cellophane tape, masking tape, etc., from ornamental metal surface prior to cleaning.</li> </ol> </li> <li>Application <li>Brush apply chemical cleaner to ornamental metal surfaces in the concentration recommended by the manufacturer.</li> <li>Agitate surface with bronze wool, stainless steel wool or synthetic cleaning pad as appropriate to metal type and surface conditions. Follow direction of grain in metal. Do not scratch or abrade surface.</li> <li>Thoroughly sponge or cloth rinse surface with clean water to remove chemical cleaner and loosened dirt.</li> <li>Wipe surface completely dry with clean soft cloths.</li> </ol> </li> </ol> </li> <li>Removing Heavy Deposits of Soiling and Oxide Accumulations from Aluminum <ol> <li>Maintain paintwork on aluminum annually. Remove all paint which is loose or flaking. It is not necessary to remove previous paint coatings if these are sound, hard, and firmly adherent, and are known to be conventional drying oil paint types, unless a sophisticated modern paint is to be applied such a two-part epoxide resin.</li> <li>Avoid applying cleaning solution to exterior aluminum surfaces in direct sun, as these become very hot, and the detergent or soap solution will dry in streaks before rinsing. These streaks can very easily become permanent and cannot be removed without abrasion.</li> <li>Cleaning heavy deposits of soiling: <li>Use a solvent-detergent mixture, or a mixture made with 1 oz. non-ionic detergent (nonyphenol condensate at 25 percent) and one ounce white spirits per gallon of water. Agitate mixture occasionally.</li> <li>Apply mixture to aluminum using a clean sponge.</li> <li>Rinse area thoroughly with clean, clear water and allow to dry.</li> </ol> </li> <li>Removing loose oxide accumulations: <li>Mix a soap solution of two to three ounces of domestic soap flakes or 1/4 pint of liquid soap per gallon of water.</li> <li>Scrub the aluminum surface with the soap solution using a light-weight scrubbing machine, natural or nylon bristle brush.</li> <li>Rinse area thoroughly with clean, clear water and allow to dry.</li> </ol> </li> <li>Removing white oxide patches from a smooth aluminum surface: <li>Mix a solution of 1/4 ounce of non-ionic detergent (nonyphenol condensate at 25 percent) per gallon of water.</li> <li>Apply the solution using natural or nylon bristle brushes if necessary to remove hard deposits.</li> <li>For highly corroded or stained areas, use etching cleaners may be permitted. Use only on bare aluminum and not on anodized aluminum, as etching cleaners tend to remove some of the metal surface. Use extreme caution when working with etching cleaners. These are strong acid and alkaline-based cleaners and must be rinsed thoroughly and neutralized if necessary.</li> </ol> </li> <li>If the deterioration spots are tough, using fine abrasives such as pumice powder and synthetic fiber scouring pads grades equivalent to (0000 to 000) is permitted along with the etching cleaners.</li> <li>In some extreme cases, it may be necessary to use special cleaning techniques requiring special power equipment such as steam cleaners, rotary fine wire brushes and abrasive blasting. The decision to use these treatments must be done in consultation with the Architect.</li> </ol> </li> <li>Cleaning Dirt, Soiling, and Discoloration from Exterior Copper Elements <ol> <li>Mix four ounces of copper sulfate, 1/2 gallon of lukewarm water, and 1/8 ounce of nitric acid.</li> <li>Apply the solution to the copper surface using a cellulose sponge mop or similar hand applicator.</li> <li>Avoid applying cleaning solution to metal in direct sun, as the detergent or soap solution will dry in streaks before rinsing. These streaks can very easily become permanent and cannot be removed without abrasion.</li> <li>Water/rinsing method: Surfaces shall be rinsed with water after cleaning. Rinse water will be collected and disposed of as stipulated. Rates of water pressure shall be 200-300 psi at 3-6 gpm.</li> </ol> </li> <li>Cleaning Brass and Bronze: <ol> <li>Vacuum-clean using nozzle attachment with a brush. A bristle brush or a toothbrush may help to raise dust from crevices.</li> <li>Remove surface grime as possible with plain non-ionic soap that is Architect-approved in a three percent solution in water. Use deionized or distilled water only, and rinse thoroughly.</li> <li>For excessive grease, an approved non-ionic detergent may be used in mineral spirits in a three percent solution; rinse with straight mineral spirits.</li> <li>Calcareous (lime or hard water) deposits may respond to a 10 percent solution of regular sodium hexametaphosphate in distilled or deionized water. Allow the solution to soak into the crust and then remove by scrubbing with stiff natural or nylon brushes. Rinse thoroughly in distilled water.</li> </ol> </li> <li>Cleaning Staining and Corrosion on Ferrous Metal <ol> <li>Mechanical and abrasive methods of cleaning may damage historic fabric. Only an experienced professional may perform this method of cleaning, and only upon approval of the Architect.</li> <li>Use of abrasives, liquids, or solvents when cleaning or stripping ferrous metals is permitted. Take special care to protect all adjacent materials, and do not use this procedure on metals other than those specified in the summary.</li> <li>Mechanical/Abrasive Method include sanding blocks or simple sand paper, flexible sandpaper wheels, and rotary wire brushes made to be chucked into a power drill and even the limited use of wet and dry air-abrasive cleaning.</li> <li>The use of controlled air-abrasive cleaning with a fine grit is allowed for cast iron features and on heavier wrought iron sections. A successful job is directly related to the skill of the operator. The individual must be able to judge pressure, distance to work surface, and grit of abrasive, and be diligent about masking all other surfaces. <li>Dry air-abrasive cleaning: No water is involved in process. Excessive amounts of dust are produced which may be illegal in local municipality. Airborne dust which may contain lead will also be a problem.</li> <li>Wet air-abrasive cleaning (preferred method): Water is mixed with abrasive and air to cut down on dust generated. This method is useful in washing soluble iron salts from pitted areas.</li> </ol> </li> <li>Water/rinsing method: Surfaces shall be rinsed with water after cleaning. Rinse water will be collected and disposed of as stipulated. Rates of water pressure shall be 200-300 psi at 3-6 gpm.</li> </ol> </li> </ol>

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