Specification:Removing wood stains from concrete

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=GENERAL=

SUMMARY
 This procedure includes guidance on removing wood stains from concrete using a hypochlorite solution. Wood stains on concrete may appear as yellow or brown in color. Stains from rotten wood may appear as chocolate brown in color. Safety Precautions:  DO NOT save unused portions of stain-removal materials. DO NOT store any chemicals in unmarked containers. EXCELLENT VENTILATION MUST BE PROVIDED WHEREVER ANY SOLVENT IS USED. USE RESPIRATORS WITH SOLVENT FILTERS. No use of organic solvents indoors should be allowed without substantial air movement. Use only spark-proof fans near operations involving flammable liquids. Provide adequate clothing and protective gear where the chemicals are indicated to be dangerous.</li> Have available antidote and accident treatment chemicals where noted.</li> </ol> </li> See Specification:General project guidelines for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections: <ol> Safety Precautions</li> Historic Structures Precautions</li> 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 State Historic Preservation Officer (SHPO). =PRODUCTS=

MATERIALS
<ol type="A">

Glycerol (C3H8O3): <ol> A sweet syrupy hygroscopic trihydroxy alcohol usually obtained by the saponification of fats and used especially as a solvent and plasticizer.</li> Other chemical or common names include Glycerine; Glyceryl hydroxide; Glycyl alcohol; 1,2,3-propanetriol; Propenyl alcohol.</li> Potential Hazards: FLAMMABLE.</li> Available from chemical supply house, drug store or hardware store.</li> </ol> </li> Sodium Hypochlorite (NaOCl): <ol> <li>An unstable salt produced usually in aqueous solution and used as a bleaching and disinfecting agent.</li> <li>Other chemical or common names include Bleaching solution*; Household bleach*; Laundry bleach*; Solution of chlorinated soda*.</li> <li>Potential Hazards: CORROSIVE TO FLESH.</li> <li>Available from chemical supply house, grocery store or supermarket, hardware store or janitorial supply distributor.</li></ol> -OR- <li>Job-prepared Hypochlorite: Made by user, see 03710-01-S for guidance on preparation.</li> <ol> <li>Calcium Hypochlorite (CaCl2O2): <li>A white powder used especially as a bleaching agent and disinfectant.</li> <li>Other chemical or common names include Chlorinated calcium oxide; Bleaching powder*; Calcium oxymuriate*; Chloride of lime*; Chlorinated lime*; Hypochlorite of lime*; Oxymuriate of lime*.</li> <li>Potential Hazards: CORROSIVE TO FLESH; FLAMMABLE (WHEN IN CONTACT WITH ORGANIC SOLVENTS).</li> <li>Available from chemical supply house, dry cleaning supply distributor, drugstore or pharmaceutical supply distributor, janitorial supply distributor, swimming pool supply distributor, or water and sanitation supply distributor.</li> </ol> </li> <li>Sodium Orthophosphate: <li>Other chemical or common names include Tribasic sodium phosphate; Trisodium orthophosphate; Trisodium phosphate; TSP*; Phosphate of soda*.</li> <li>Potential Hazards: CORROSIVE TO FLESH.</li> <li>Available from chemical supply house, grocery store or supermarket or hardware store.</li> </ol> </li> </ol> </li> <li>Clean, potable water</li> <li>Accessible source of water, soap and towels for washing and rinsing in case of emergencies associated with the use of chemicals</li> </ol>

EQUIPMENT
<ol type="A"> <li>Stiff, natural bristle brushes</li> <li>Clean, dry cloths</li> </ol> =EXECUTION=

PREPARATION
<ol type="A"> <li>Protection: <ol> <li>Provide adequate wash solutions (i.e. water, soap and towels) before starting the job.</li> <li>Whenever acid is used, the surface should be thoroughly rinsed with water as soon as its action has been adequate. Otherwise it will continue etching the concrete even though the stain is gone.</li> </ol> </li> </ol>

ERECTION, INSTALLATION, APPLICATION
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<li>First, scrub the surface thoroughly with a solution of 1 part glycerol in 4 parts water.</li> <li>Next, scrub the stained area with a hypochlorite solution. Use job-prepared hypochlorite (see 03710-01-S for guidance on preparation), or dilute 1 part household bleach (5% sodium hypochlorite) with 4 to 6 parts water.</li> <li>Rinse thoroughly with clean, clear water and allow to dry.</li> <li>Repeat the process as required to achieve the desired level of cleanliness.</li> </ol>