Specification:Removing paint-based graffiti from concrete

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=GENERAL=

SUMMARY
 This procedure includes guidance on removing paint-based graffiti from concrete by scrubbing with proprietary cleaners or chemical solvents. For guidance on removing ink-based graffiti or stains, see 03710-24-R. 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. 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 Historical Preservation Officer (SHPO). =PRODUCTS=

MATERIALS
<ol type="A">

Denatured Alcohol: <ol> Other chemical or common names include Methylated spirit*.</li> Potential hazards: TOXIC AND FLAMMABLE.</li> Available from hardware store, paint store or printer's supply distributor.</li> Denatured alcohol, which carries no liquor tax, should be a satisfactory substitute for ethyl alcohol for stain removing purposes.</li> </ol> </li> Dichloromethane: This is one of the best nonproprietary cleaners because it can be washed off with water. <ol>

Other chemical or common names include Methylene bichloride; Methylene chloride; Methylene dichloride.</li> <li>Potential Hazards: TOXIC.</li> <li>Available from chemical supply house, dry cleaning supply distributor, paint store, photographic supply distributor (not camera shop), or printer's supply distributor.</li> </ol> </li> <li>Oxalic Acid (COOH)2 or (H2C2O4): <ol> <li>A poisonous strong acid that occurs in various plants as oxalates and is used especially as a bleaching or cleaning agent and in making dyes.</li> <li>Other chemical or common names include Ethanedioic acid.</li> <li>Potential Hazards: TOXIC; CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS.</li> <li>Available from chemical supply house, dry cleaning supply distributor, drugstore or pharmaceutical supply distributor, hardware store, or photographic supply distributor (not camera shop). (Often sold under a manufacturer's brand name; the chemical name may appear on the label.)</li> </ol> </li> <li>Hydrogen Peroxide (H202): <ol> <li>An unstable compound used especially as an oxidizing and bleaching agent, an antiseptic, and a propellant.</li> <li>Other chemical or common names include Peroxide of hydrogen*; Solution of hydrogen dioxide*; Superoxol*; (hydrogen peroxide is commonly sold as a 3% solution; Superoxol is a 30% solution; Superoxol causes flesh burns; 3% hydrogen peroxide does not).</li> <li>Potential Hazards: TOXIC (when concentrated); CORROSIVE TO FLESH (gasoline, kerosene and mineral spirits are each a mixture of compounds from petroleum, all of which fall within a specified range of properties); FLAMMABLE (in high concentration).</li> <li>Available from chemical supply house, drugstore, pharmaceutical supply distributor, or hardware store.</li> </ol> </li> <li>Anti-graffiti coating for concrete</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> <li>Alternative Materials for Stain Removal: <ol> <li>Solvents: Methyl Ethyl Ketone: <li>Other chemical or common names include 2-butanone; MEK*.</li> <li>Potential Hazards: TOXIC AND FLAMMABLE.</li> <li>Available from chemical supply house, hardware store or paint store.</li> -OR- Methyl Isobutyl Ketone: <li>Other chemical or common names include Asymmetric ethyl methyl acetone; 3-methyl-2-pentanone; Secondary butylmethyl ketone; MIBK*.</li> <li>Potential Hazards: TOXIC AND FLAMMABLE.</li> <li>Available from chemical supply house, hardware store or paint store.</li> -OR- Xylene (C8H10): <li>Any of three toxic, flammable, oily, isomeric, aromatic hydrocarbons that are di-methyl homologues of benzene and are obtained from wood tar, coal tar, or petroleum distillates; Also a mixture of xylenes and ethyl-benzene used chiefly as a solvent.</li> <li>Other chemical or common names include Xylol; P-xylene; 1,4-dimethyl benzene.</li> <li>Potential Hazards: TOXIC AND FLAMMABLE.</li> <li>Available from chemical supply house, hardware store, paint store or printer's supply distributor.</li> </ol> </li> <li>Proprietary cleaners containing combinations of materials such as sodium hydroxide or other alkali, dichloromethane or other solvent, and detergent.</li> </ol> </li> </ol>

EQUIPMENT
<ol type="A"> <li>Stiff bristle brushes (non-metallic)</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
<ol type="A">

<li>Using a stiff bristle brush, scrub dichloromethane into the concrete surface.</li> <li>Wait about 2 minutes and rinse thoroughly with clean, clear water. Use a scrub brush to work the water into the concrete pores. If any solution gets on the skin, rinse off with soap and water immediately.</li> <li>Bleach any remaining paint pigment using a concentrated solution of oxalic acid or a strong solution of hydrogen peroxide. <ol> <li>Test the bleach on a small area to be sure it does not excessively or unevenly lighten the surface.</li> <li>If the test is satisfactory, apply the solution liberally to the surface. Work the solution vigorously into the concrete pores using a stiff bristle brush and allow to sit for 10 to 15 minutes.</li> <li>Thoroughly rinse the area with clean, clear water and allow to dry.</li> </ol> </li>

-OR- <li>Use a proprietary cleaning agent (see Section 2.01 H.2 for alternatives). Follow the manufacturer's instructions for application requirements and precautions. Success will be dependent upon the type of cleaner selected and the level of experience or skill of the operator.</li> <li>When the graffiti has been sufficiently removed, apply an anti-graffiti coating from which any new graffiti can be easily removed. Use only anti-graffiti coatings which do not change the color of the surface.</li> </ol>