Cleaning and stripping paint from plaster surfaces
PART 1---GENERAL1.01 SUMMARY A. This procedure includes guidance on cleaning and chemically removing paint from existing plaster surfaces.PART 2---PRODUCTS2.01 MANUFACTURERS A. Diedrich Technologies, Inc. 7373 South 6th Street Oak Creek (Milwaukee), WI 53154 800/323-3565 or 414/764-0058 B. Red Devil, Inc. 2400 Vauxhall Road Union, NJ 07083-1933 800/423-3845 or 201/688-69002.02 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. Trisodium Phosphate: NOTE: THIS CHEMICAL IS BANNED IN SOME STATES SUCH AS CALIFORNIA. REGULATORY INFORMATION AS WELL AS ALTERNATIVE OR EQUIVALENT CHEMICALS MAY BE REQUESTED FROM THE ENVIRONMENTAL PROTECTION AGENCY (EPA) REGIONAL OFFICE AND/OR THE STATE OFFICE OF ENVIRONMENTAL QUALITY. 1. Strong base-type powdered cleaning material sold under brand names, such as that manufactured by Red Devil, Inc. 2. Other chemical or common names include Sodium Orthophosphate; Tribasic sodium phosphate; Trisodium orthophosphate; TSP*; Phosphate of soda*. 3. Potential Hazards: CORROSIVE TO FLESH. 4. Available from chemical supply house, grocery store or supermarket or hardware store. B. Commercial paint remover, such as "Diedrich 400 - Enviro- Safe Strip" (Diedrich Technologies, Inc.), or approved equal. C. For Glaze Remover: 1. 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 should be a satisfactory substitute for ethyl alcohol for stain removing purposes. 2. Mineral Spirits: a. A petroleum distillate that is used especially as a paint or varnish thinner. b. Other chemical or common names include Benzine* (not Benzene); Naphtha*; Petroleum spirits*; Solvent naphtha*. c. Potential Hazards: TOXIC AND FLAMMABLE. d. Safety Precautions: 1) AVOID REPEATED OR PROLONGED SKIN CONTACT. 2) ALWAYS wear rubber gloves when handling mineral spirits. 3) If any chemical is splashed onto the skin, wash immediately with soap and water. e. Available from construction specialties distributor, hardware store, paint store, or printer's supply distributor. 3. Acetone (C3H6O): a. A volatile fragrant flammable liquid ketone used chiefly as a solvent and in organic synthesis and found abnormally in urine. b. Other chemical or common names include Dimethyl ketone; Propanone c. Potential Hazards: VOLATILE AND FLAMMABLE SOLVENT d. Available from chemical supply house or hardware store. D. Clean, potable water2.03 EQUIPMENT A. Clean, dry cloths B. Sponge or heavy-nap cloth C. Soft, fiber bristle brushes D. Putty knifePART 3---EXECUTION3.01 PREPARATION A. Protection: 1. Protect surrounding surfaces from damaged resulting from chemical cleaning and paint stripping work. 2. Dispose of by-products from cleaning and paint stripping operations by legal means and in manner which prevents damage to other surfaces. 3. Develop a work plan indicating recommended treatments for surfaces/areas. B. Surface Preparation: Prior to cleaning and stripping work, remove cellophane tape, masking tape, etc. from surface.3.02 ERECTION, INSTALLATION, APPLICATION A. Cleaning Existing Plaster Surfaces: 1. Mix TSP with warm water to create cleaning solution. 2. Scrub surface with a cloth, sponge or soft-fibered brush and cleaning solution. a. Proceed with cleaning and stripping in an orderly manner; work from bottom to top of each surface and from one end of each surface to the other. b. Perform each cleaning and stripping method indicated in a manner which results in uniform coverage of all surfaces, including corners, moldings, interstices and which produces an even effect without streaking or damage to surfaces. 3. Sponge rinse surface thoroughly using clean water to completely remove chemical residue and soil. Change rinse water frequently. a. Rinse off chemical residue and soil by working upwards from bottom to top of each surface and from one end of each surface to the other. NOTE: THERE IS SOME DIFFERENCE OF OPINION AS TO WHETHER IT IS BEST TO WASH A WALL WORKING FROM THE TOP DOWN OR FROM THE BOTTOM UP. BOTTOM UP IS SAFER BECAUSE SOLUTION STREAKS RUNNING DOWN ON A DIRTY WALL CANNOT BE REMOVED. THE IMPORTANT THING IS TO WORK DRY ENOUGH TO AVOID DRIPS. 4. Repeat process as required. 5. Wipe the surface with a dry clean cloth to prevent streaking. B. Stripping Paint from Plaster Surfaces: 1. Carefully apply commercial stripper to painted surface with a brush. Follow manufacturer's instructions and precautions. -OR- Prepare a glaze remover: Mix 5 parts denatured alcohol, 3 parts mineral spirits and 1 part acetone and apply to the surface. 2. Allow commercial stripper or glaze remover to remain on surface for length of time recommended by manufacturer and required to emulsify paint build- up. 3. Carefully remove emulsified paint with a putty knife. 4. Repeat process as many times as required to remove paint build-up. 5. Neutralize chemical stripper by wiping surface with a cloth wet with clean water. Change water frequently.3.02 ADJUSTING/CLEANING A. Upon completion of this work, all floors, walls and other adjacent surfaces that are stained, marred, or otherwise damaged by work under this section shall be cleaned and repaired and all work and the adjacent areas shall be left in a clean and perfect condition. B. All completed work shall be adequately protected from damage by subsequent building operations and effects of weather. Protection shall be by methods recommended by the manufacturer.
Source: U.S. General Services Administration Historic Preservation Technical Procedures