Chemically Removing Paint from Wood Features

Procedure code:
640007S
Source:
Division:
Wood and Plastics
Section:
Architectural Woodwork
Last Modified:
08/19/2016

PREFACE

Projects involving paint removal are subject to state and federal laws on lead paint abatement, disposal and use of volatile organic compounds (VOCs). Specified products may not be permitted or appropriate for all locations. Products containing chemicals known to present health or environmental hazards should be used only as a last resort, where permissible, in accordance with manufacturer's directions and government requirements. Test milder formulations for effectiveness before proceeding to stronger alternatives.

PART 1---GENERAL

1.01 SUMMARY

  1. This specification provides guidance on removing paint from interior and exterior wood features using chemical methods.

  2. Chemical strippers should be used on extremely intricate details that might be scorched by too long of an exposure to the blast from a heat gun. They are also useful as final cleanup after paint removal using one of the thermal methods. Follow manufacturer's instructions.

  3. Safety Precautions:

    1. Workers shall wear appropriate clothing to protect themselves against the harmful effects of paint stripping activity. Old paint layers will likely contain lead. Avoid breathing paint dust during removal.

    2. No food or drink shall be allowed near any work station so as to prevent contamination from paint chips, dust or chemical removers which contain lead and other toxic substances.

    3. Protective clothing shall be removed at the end of each day and kept at the site to prevent workers from tracking dust and paint chips to other parts of the site or to their homes.

    4. Wash hands and face often, especially before eating and at the end of the day.

  4. Read "General Project Guidelines" along with this specification. 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). The 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)

  5. See also "Supplemental Guidelines for Removing Paint from Interior and Exterior Wood Surfaces".

1.02 REFERENCES

  1. AWI Quality Standard: Comply with applicable requirements of "Architectural Woodwork Quality Standards" 8th Edition (2005), published by the Architectural Woodwork Institute (AWI), except as otherwise indicated.

  2. Information on VOC levels in paint removal products is available in "Guide to Choosing Paint Stripping Products: Safety Precautions" (May 2014), published by the California Department of Public Health, Hazard Evaluations System and Information Service

1.03 DEFINITIONS

  1. Chemical Methods: as used herein shall apply to the use of commercial chemical paint strippers.

    1. "Do-it-yourself" chemicals available through local paint stores, hardware stores, building supply centers.

    2. Professional, heavy-duty type used by paint removal contractors, generally only available through the manufacturer and/or qualified contractors. May also be available by special order from local paint stores.

  2. Chemical paint strippers are divided into solvent-based, caustic-based, and alternative-based strippers.

    1. Solvent-based: Most use methylene chloride to dissolve and swell varnish and/or paint film for removal. Some are water-rinsable.

      1. Liquid: fast working; best used on horizontal surfaces, or for clean-up when using thermal methods.

      2. Semi-paste: good for vertical and overhead surfaces, rounded features, intricate details.

      3. Will soften oil-based paints, lacquers, varnishes and synthetic baked finishes.

      4. Can be used on both hardwoods and softwoods without changing the color of the wood so that the feature can be refinished with a clear finish if desired.

      5. Non-water-rinsable products are safe for use on most water-based wood glues.

      6. Before refinishing, surface must be completely cleaned of stripper residue but neutralization of the surface is not required.

      7. Benzol is a highly toxic and highly flammable solvent often used in the past in formulating solvent-based paint and varnish removers. Due to the hazard it poses, it is no longer recommended for use.  

    2. Caustic-based: Use sodium hydroxide, and to a lesser extent potassium hydroxide, to decompose the binder in the coating. Proprietary products are mostly for commercial rather than "do-it-yourself" use.

      1. Liquid: used for dip-stripping of shutters, doors, furniture, etc.

      2. Semi-paste: basis for most professional proprietary products; good or horizontal, vertical and overhead surfaces, also intricate details.

      3. Will work on most types of coatings from oil- based and latex paints to sophisticated epoxy- ester finishes. Check with manufacturer for appropriate usage.

      4. Will darken hardwoods so should not be used on features made from oak, walnut, mahogany, and other hardwoods if a clear finish is to be used.

      5. Because they are water-rinsable, caustic strippers will likely raise the grain on many woods so extra finish steps, such as sanding, may be required regardless of whether the surface is to be painted or given a clear finish.

      6. Caustic strippers will dissolve many types of wood glues--a problem when stripping shutters, wood veneers, plywood, etc.

      7. Surface must be neutralized with mild acid wash before refinishing.

    3. Alternative-based: Water-based products which use nonflammable, biodegradable active ingredients to soften the paint. Most are water-rinsable, or removed with common household cleaners. Active ingredients include dibasic acid esters. Products are typically in semi-paste form.

      1. Separate formulas for clear finish removal versus paint removal.

      2. Require considerably more time to soften the old finish than either methylene-chloride-based or caustic-based strippers.

      3. Can be used on both hardwoods and softwoods without discoloring the wood.

1.04 DELIVERY, STORAGE AND HANDLING

All chemicals shall be stored in metal cabinets. No cans shall be left open or out of the cabinet overnight.

PART 2---PRODUCTS

2.01 MANUFACTURERS

  1. For Chemical Paint Removers:

    1. The 3M Company

    2. Diedrich Technologies, Inc.

Schenectady, NY

1-800-283-3888

NOTE: Diedrich Technologies paint removers are only available through authorized suppliers and contractors

    1. Dumond Chemicals, Inc.

West Chester, PA (corporate office)

1-800-245-1191 or 609-655-7700

info@dumondglobal.com

    1. Old Master's

Orange City, IA

51041

1-800-747-3436 or

712-737-3436

    1. Savogran Company

Norwood, MA

1-800-225-9872

    1. W. M. Barr & Co.

Memphis, TN

1-800-398-3892

  1. For Fumed Silica:

    1. Evonik (Aerosil)

    2. Cabot Corporation (Cab-o-sil)

    3. Dow Corning (Wacker Chemie)

    4. OCI (Konasil)

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 (*).

  1. Paint removers such as any of the following:

    1. Paint Removers with low or no VOCs:

      1. 10101 Safest Stripper Paint And Varnish Remover (alternative-based, the 3M Company)

      2. Envirestrip Environmental Paint Remover (alternative-based, Diedrich Technologies, Inc.)

      3. Enviro Klean Safety Peel 1 (alternative-based, ProSoCo, Inc.)

      4. Smart Strip (alternative-based, Dumond Chemicals, Inc.)

NOTE: methylene chloride-free products will require longer dwell times on surfaces than that required for products that contain methylene chloride as their main active ingredient.

-OR-

    1. Paint removers with intermediate levels of VOCs:

      1. Peel Away 1 (caustic-based, Dumond Chemicals, Inc.)

      2. Peel Away 7 (solvent-based, Dumond Chemicals, Inc.)

      3. Biodegradable Strypeeze (alternative-based, Savogran Company)

-OR-

    1. "Last Resort" paint removers (products that have been traditionally used but have high VOCs):

      1. Original Semi-paste Strypeeze (solvent-based, Savogran Company)

      2. Klean Strip Premium Stripper and Premium Sprayable Stripper (W. M. Barr & Co.)

      3. TM-4 Heavy Duty Remover (solvent-based, Old Master's)

      4. 505 Special Coatings Stripper (solvent-based, Diedrich Technologies, Inc.)

NOTE: The above four products contain methylene chloride, a known carcinogen. Methylene chloride 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. 606 Multi-Layer Paint Remover (caustic-based, Diedrich Technologies, Inc.)

  1. Plastic sheeting

  2. Cornstarch or fumed silica such as "Cab-o-sil" (Samuel Cabot, Inc.), or approved equal.

    1. Used to thicken chemicals so they will adhere to vertical surfaces and ceilings.

    2. Fumed silica is also used as a filler in epoxy repairs.

    3. Available from grocery store.

  3. Denatured alcohol (to remove last traces of chemical residue):

    1. Other chemical or common names include Methylated spirit*.

    2. Potential hazards: TOXIC AND FLAMMABLE.

    3. Available from hardware store, paint store or printer's supply distributor.

    4. Denatured alcohol should be a satisfactory substitute for ethyl alcohol for stain removing purposes.

  4. For caustic-based paint strippers, neutralizer as recommended by paint stripper manufacturer, to return surface to neutral pH prior to refinishing.

  5. Steel wool, cheese cloth, or other cloths for final clean-up.

  6. Phenolphthalein: Used to test pH of a surface after stripping with alkaline chemicals. Available at some drug stores or chemical supply houses

2.03 EQUIPMENT

  1. Steel wool, scrapers and small picks to remove sludge.

  2. Metal containers such as old coffee cans to dispose of sludge.

  3. Putty knives and paint scrapers (of different shapes and flexibility).

  4. Natural bristle brushes or plastic spatulas as recommended by paint stripper manufacturer to apply stripper.

  5. Duct tape.

  6. Spray equipment (only if recommended or provided by manufacturer).

PART 3---EXECUTION

3.01 EXAMINATION

  1. One of the main reasons for paint failure is excess moisture, both from internal and external sources. Before work is begun on removing the existing paint film or otherwise preparing the surface, all flashing and gutters and downspouts shall be inspected and repaired or replaced as required. Make provisions as required for removing excess moisture from areas of high humidity.

  2. All wood elements shall be carefully inspected for rot and, if deteriorated, marked for later replacement, after the paint has been removed.

3.02 PREPARATION

  1. Protection

    1. General: Comply with recommendations of manufacturers of paint strippers for protecting surrounding building surfaces against damage from exposure to their products.

    2. Protect adjacent surfaces, including grass, shrubs and trees with paper, drop cloths and other means. Items not painted which are in contact with or adjacent to painted surfaces shall be removed or protected prior to surface preparation and painting operations.

    3. All waste material shall be collected at the end of each work day and disposed of in a manner consistent with local environmental regulations. It is considered Hazardous Waste.

    4. Work area shall be sealed to prevent the spread of paint dust and debris beyond the work site.

    5. All rags shall be disposed of nightly and removed from the building.

    6. Adequate ventilation should be provided in each area where solvents and strippers are used.

    7. A fully charged fire extinguisher suitable for solvent fires shall be kept in each area where work is going on.

    8. Contractor shall provide multiple fans with high CFM to move fumes out of the building and away from areas where work is being done.

    9. Compressor motors, heat lamps, etc., must be of explosion proof type.

    10. No spraying of solvents or strippers permitted unless specifically allowed by the manufacturer of the product being used.

    11. Do not operate a building's central heating system while stripping interior wood features using chemicals, or for several days afterwards. Chloride compounds in the vapors of these removers can combine with the combustion air and move into the furnace-burner compartment of the heating system. Chemical reactions occur with the flue gasses which create highly corrosive acids which can condense on the heat exchanger, vent piping, etc. Once started, the corrosion created by this acid, cannot be stopped.

    12. After paint removal is complete, all areas around the site shall be cleaned of all paint dust and debris, and such debris shall be properly disposed of in a manner consistent with local environmental regulations. Vacuums used to clean up dust shall be equipped with High Efficiency Particulate Air (HEPA) filters.

  2. Surface Preparation: Use scrapers of a variety of sizes and shapes, whose edges have been rounded, to remove loose paint before removal using chemicals.

3.03 ERECTION, INSTALLATION, APPLICATION

NOTE: WORK IN WELL-VENTILATED AREA TO AVOID INHALATION OF TOXIC FUMES.

  1. Lay the chemicals onto the surface in the manner and amount recommended by the manufacturer.

  2. Allow to sit or "dwell" according to the manufacturer's instructions. If required, cover with plastic wrap.

  3. Remove the sludge using scrappers and steel wool. A second application may be required on those areas where paint is especially thick and/or the detail is intricate.

  4. After removal has been completed, rub all surfaces down with denatured alcohol or water (for water-rinsable strippers only) to remove all traces of chemical residue.

    1. For solvent-based strippers:

      1. Most solvent-based chemicals also contain wax to help retard evaporation during the dwell period. Unless completely removed, this wax will inhibit the performance of the new finish.

      2. Thoroughly rub all surfaces, and especially deep crevices, with denatured alcohol to remove all traces of remover. Mineral spirits will work as well, but it may also leave a somewhat oily residue.

    1. For caustic-based strippers:

      1. Carefully and completely neutralize feature as directed by manufacturer to return surfaces to a neutral pH.

      2. To test whether all chemicals have been removed dissolve a 2" piece of phenolphthalein in denatured alcohol.

      3. Brush the solution onto the surface. If it turns a shade from pink to magenta there is still chemical residue.

      4. Treat the surface with additional neutralizer and continue testing until there is no color change in the phenolphthalein solution. This test will work with any alkaline product.

      5. Testing the damp surface with litmus paper until a pH level of 7 is achieved will also work if phenolphthalein is not available.

    1. For alternative-based strippers: These products contain neither waxes nor strong alkalis so clean-up is simplified. Follow manufacturer's instructions for removal or residue.

  5. For guidance on repainting or refinishing wood features, see:

    1. "Primers and Paints for Wood"

    2. "Surface Preparation for Painting Wood"

    3. "General Guidelines for Painting Exterior and Interior Surfaces"

    4. "Refinishing Interior Wood"

3.04 ADJUSTING/CLEANING

  1. Upon completion of this work, all floors, walls and other adjacent surfaces that are stained, marred, otherwise damaged by work shall be cleaned and repaired and all work and the adjacent areas shall be left in a clean and orderly condition.

  2. 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 of installed materials and as approved by the Architect.

END OF SECTION

Last Reviewed 2016-08-19