REMOVING PAINT, SHELLAC AND VARNISHES FROM CONCRETE THE CLEANING OR REMOVAL OF STAINS FROM CONCRETE MAY INVOLVE THE USE OF LIQUIDS, DETERGENTS OR SOLVENTS WHICH MAY RUN OFF ON ADJACENT MATERIAL, DISCOLOR THE CONCRETE OR DRIVE THE STAINS DEEPER INTO POROUS CONCRETE. USE THE PRODUCTS AND TECHNIQUES DESCRIBED HERE ONLY FOR THE COMBINATIONS OF DIRT/STAIN AND CONCRETE SPECIFIED. PART 1---GENERAL 1.01 SUMMARY A. This procedure includes guidance on removing paint, shellac and varnishes from concrete by scrubbing and poulticing. B. Safety Precautions: 1. DO NOT save unused portions of stain-removal materials. 2. DO NOT store any chemicals in unmarked containers. 3. EXCELLENT VENTILATION MUST BE PROVIDED WHEREVER ANY SOLVENT IS USED. USE RESPIRATORS WITH SOLVENT FILTERS. NOTE: SOME OF THE SOLVENTS LISTED ARE KNOWN CARCINOGENS AND MAY BE BANNED IN SOME STATES. 4. No use of organic solvents indoors should be allowed without substantial air movement. Use only spark-proof fans near operations involving flammable liquids. 5. Provide adequate clothing and protective gear where the chemicals are indicated to be dangerous. 6. Have available antidote and accident treatment chemicals where noted. C. See 01100-07-S for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections: 1. Safety Precautions 2. Historic Structures Precautions 3. Submittals 4. Quality Assurance 5. Delivery, Storage and Handling 6. Project/Site Conditions 7. Sequencing and Scheduling 8. General Protection (Surface and Surrounding) These guidelines should be reviewed prior to performing this procedure and should be followed, when applicable, along with recommendations from the Regional Historic Preservation Officer (RHPO). PART 2---PRODUCTS 2.01 MANUFACTURERS A. ProSoCo, Inc. 755 Minnesota Avenue P.O. Box 1578 Kansas City, KS 66117 913/281-2700 2.02 MATERIALS NOTE: Chemical products are sometimes sold under a common name. This usually means that the substance is not as pure as the same chemical sold under its chemical name. The grade of purity of common name substances, however, is usually adequate for stain removal work, and these products should be purchased when available, as they tend to be less expensive. Common names are indicated below by an asterisk (*). A. For Removing Fresh Paint: 1. Scouring powder and detergent B. For Removing Cured Paint, Enamel, Lacquer or Oil-based Varnish: 1. For Formula 1: (see Section 3.02 B.) Benzene (C6H6): a. A colorless, volatile, flammable, toxic, liquid, aromatic hydrocarbon used in organic synthesis, as a solvent and as a motor fuel. b. Other chemical or common names include Benzol; Benzole; Phene; Phenyl hydride; Coal naphtha*; Motor benzol*. c. Potential Hazards: FLAMMABLE. d. Available from automotive supply distributor, chemical supply house, dry cleaning supply distributor, hardware store or paint store. e. Benzene and benzine should not be confused. Benzene is a distinct chemical compound obtained from coal tar. Benzine is a mixture of aromatic hydrocarbons of similar boiling points derived from petroleum. Denatured Alcohol: a. Other chemical or common names include Methylated spirit*. b. Potential hazards: TOXIC AND FLAMMABLE. c. Available from hardware store, paint store or printer's supply distributor. d. Denatured alcohol, which carries no liquor tax, should be a satisfactory substitute for ethyl alcohol for stain removing purposes. Ethylene Dichloride: a. A colorless pungent flammable gaseous or volatile liquid used especially as a local surface anesthetic. b. Other chemical or common names include 1,2-dichlorethane; Ethylene chloride; Glycol dichloride. c. Potential Hazards: TOXIC AND FLAMMABLE. d. Available from automotive supply distributor, dry cleaning supply distributor, or paint store. Methyl Acetone: a. A mixture of various proportions of acetone (47 to 51%), methyl acetate (27.5 to 31%) and methyl alcohol (20 to 25%). b. Potential Hazards: FLAMMABLE. c. Available from chemical supply house, paint store, or photographic supply distributor (not camera shop). -OR- 2. For Formula 2: Sodium Hydroxide (NaOH): a. A white brittle solid that is a strong caustic base used especially in making soap, rayon, and paper. b. Other chemical or common names include Caustic soda*; Hydrate of soda*; Hydrated oxide of sodium*; Lye*; Mineral alkali*; Soda lye*; Sodic hydrate*; Sodium hydrate*. c. Potential Hazards: CORROSIVE TO FLESH AND FLAMMABLE (WHEN IN CONTACT WITH ORGANIC SOLVENTS). d. Available from chemical supply house, drugstore or pharmaceutical supply distributor, hardware store, or paint store. -OR- 3. Commercial paint remover such as "Sure Klean 509 Paint Stripper" (ProSoCo, Inc.), or approved equal. C. For Removing Shellac: 1. Wood Alcohol: a. Other chemical or common names include Carbinol; Methanol; Methyl alcohol; Methyl hydrate; Methyl hydroxide; Methyllic alcohol; Colonial spirits*; Columnian spirits*; Green wood spirits*; Manhattan spirits*; Pyroligneous spirit*; Pyroxylic spirit*; Standard wood spirits*; Wood naphtha*; Wood spirit*. b. Potential Hazards: TOXIC AND FLAMMABLE. c. Available from automotive supply distributor, chemical supply house, dry cleaning supply distributor, drugstore or pharmaceutical supply distributor, hardware store, paint store, or photographic supply distributor (not camera shop). -OR- Denatured alcohol (see 2.02 B.2. above) 2. Hydrochloric Acid (30-35%): a. A strong corrosive irritating acid. b. Other chemical or common names include Chlorhydric acid; Hydrogen chloride; Muriatic acid* (generally available in 18 degree and 20 degree Baume solutions); Marine acid*; Spirit of salt*; Spirit of sea salt*. c. Potential Hazards: TOXIC, CORROSIVE TO FLESH; CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS, FLAMMABLE. d. Available from chemical supply house, drugstore or pharmaceutical supply distributor, or hardware store. -OR- Phosphoric Acid: a. A syrupy or deliquescent tribasic acid used especially in preparing phosphates (as for fertilizers), in rust-proofing metals, and as a flavoring in soft drinks. b. Other chemical or common names include Orthophosphoric acid. c. Potential Hazards: CORROSIVE TO FLESH; CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS. d. Available from chemical supply house or hardware store. D. For Removing Old or Dried Paint: 1. Muriatic acid: (see Hydrochloric acid 2.02 C.2. above) 2. Scouring powder and detergent E. Filler material such as diatomaceous earth or talc F. Mineral water G. Clean, potable water H. Clean dry cloths or paper towels for blotting the area after treatment I. Accessible source of water, soap and towels for washing and rinsing in case of emergencies associated with the use of chemicals 2.02 EQUIPMENT A. For Poulticing: 1. Glass or ceramic container for mixing the solution 2. Wooden utensil for stirring the ingredients B. Wood or plastic spatula C. Stiff bristle brush (non-metallic) PART 3---EXECUTION 3.01 PREPARATION A. Protection: 1. Provide adequate wash solutions (i.e. water, soap and towels) before starting the job. 2. 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. 3.02 ERECTION, INSTALLATION, APPLICATION NOTE: DO NOT TRY MORE THAN ONE TREATMENT ON A GIVEN AREA UNLESS THE CHEMICALS USED FROM PRIOR TREATMENT HAVE BEEN WASHED AWAY. A. To Remove Fresh Paint: 1. Blot spilled or unwanted fresh paint with clean cloths or paper towels. DO NOT WIPE THE PAINT. THIS WILL DRIVE THE PAINT INTO THE SURFACE. 2. Scrub the surface immediately with scouring powder and clean, clear water to remove as much of the stain as possible. 3. If staining remains, wait several days and then treat like cured paint (below). B. To Remove Cured Paint, Enamel, Lacquer or Oil-Based Varnish: 1. Remove as much of loose coating as possible by brushing with a stiff (non-metallic) bristle brush. 2. Formula 1: Mix 10 parts methyl acetone, 25 parts benzene, 18 parts denatured alcohol and 8 parts ethylene dichloride. -OR- Formula 2: Mix a solution of 2.5 pounds sodium hydroxide in 1 gallon of hot water (this can be used in a poultice or applied to the surface by brush). -OR- Use a commercial paint remover. 3. Thoroughly wet the concrete surface to be treated with clean, clear water. 4. Apply the mixture to the stained area using a wood or plastic spatula and allow to dry (approximately 20-30 minutes). Be sure to spread the poultice well beyond the stained area. The liquid portion of the paste will migrate into the concrete where it will dissolve some of the staining material. Then the liquid will gradually move back beyond the concrete surface and into the poultice, where it will evaporate, leaving the dissolved staining material in the poultice. 5. When the poultice has dried, brush or scrape it off with a wooden scraper. 6. Thoroughly rinse the area with clean, clear water and allow to dry. 7. Repeat the process as necessary to achieve the desired level of cleanliness. C. To Remove Shellac: 1. Remove as much of loose coating as possible by brushing with a stiff (non-metallic) bristle brush. 2. Mix wood alcohol or denatured alcohol with diatomaceous earth or talc to form a thick paste. 3. Follow poulticing procedures in Section 3.02 B.3-7 above. 4. If a residue remains, scrub the area with scouring powder, rinse with clean, clear water and allow to dry. 5. If there is staining below the surface: a. Mix 1 part hydrochloric acid with 9 to 19 parts of water. -OR- Mix 1 part phosphoric acid in 9 parts of water. b. Wash the surface with the solution using a stiff (non-metallic) bristle brush. c. Thoroughly rinse the surface with clean, clear water and allow to dry. D. To Remove More Difficult Coatings (such as old, dried paint): 1. Remove as much of loose coating as possible by brushing with a stiff non-metallic bristle brush. 2. Mix 1 part concentrated muriatic acid, 4 parts water and 1 part detergent. 3. Apply mixture to the surface and scrub with a stiff (non-metallic) bristle brush. 4. Thoroughly rinse the surface with clean, clear water and allow to dry. 5. Repeat as necessary to achieve the desired level of cleanliness. END OF SECTION