Historic Preservation - Technical Procedures

Spectitle:
Chemically Removing Paint From And Repainting Brick Masonry
Procedure code:
0421114R
Source:
Developed For HSPG(NPS - Southeast Regional Office)
Division:
Masonry
Section:
Brick Unit Masonry
Last Modified:
11/24/2015
Details:
Chemically Removing Paint From And Repainting Brick Masonry
Last Modified:
11/24/2015

CHEMICALLY REMOVING PAINT FROM AND REPAINTING BRICK MASONRY

BEFORE UNDERTAKING ANY PROJECT INVOLVING PAINT REMOVAL, APPLICABLE
STATE AND FEDERAL LAWS ON LEAD PAINT ABATEMENT AND DISPOSAL MUST
BE TAKEN INTO ACCOUNT AND CAREFULLY FOLLOWED.  STATE AND FEDERAL
REQUIREMENTS MAY AFFECT OPTIONS AVAILABLE TO OWNERS ON BOTH PAINT
REMOVAL AND REPAINTING.  THESE LAWS, AS WELL AS ANY REQUIREMENTS
PROHIBITING VOLATILE ORGANIC COMPOUNDS (VOCs), SHOULD BE REQUESTED
FROM THE STATE HISTORIC PRESERVATION OFFICER IN EACH STATE.  (From
Preservation Brief 28, "Painting Historic Interiors")

PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on chemically removing
         paint from and repainting brick masonry.  

         NOTE:  SANDBLASTING IS NOT RECOMMENDED BY THE SECRETARY
         OF THE INTERIOR'S STANDARDS FOR REHABILITATION AND SHALL
         NOT BE USED.  HIGH-PRESSURE WATER BLASTING IS ALSO NOT
         RECOMMENDED WITHOUT ADEQUATE TESTING OR EXPERIENCE AS IT
         MAY ERODE SOFT BRICK AND DRIVE MOISTURE INTO THE WALL.

    B.   Brick, properly fired, is a durable surface which does
         not need a sacrificial coating such as paint, to protect
         it.  Painting often creates long term maintenance
         problems.  However, brick that has been painted, is
         usually NOT properly fired and needs the protection
         provided by the application of paint.  Furthermore, brick
         which has been damaged by abrasive cleaning may require
         painting in order to seal the masonry from excessive
         water penetration which, if not protected, can lead to
         further deterioration of the masonry.

    C.   Safety Precautions:

         CAUTION:  CHEMICALS OFTEN USED TO REMOVE PAINT ARE HIGHLY
         CAUSTIC AND TOXIC.

         1.   Both acids and alkalies are used in the cleaning
              process. The wrong type of acid can burn and/or
              dissolve both the brick and the mortar.  Adjacent
              and imbedded materials, i.e. glass or iron cramps,
              can also be damaged.  

         2.   Failure to properly neutralize the chemicals, or
              inadequate rinsing can cause salts, stains and
              other residues to remain on the surface of the
              brick, residues which may be impossible to remove.

    D.   Historic Structure Precautions:

         1.   Masonry buildings were sometimes painted from the
              start.  A study of all of the paint layers should
              be conducted to determine what were the original
              colors and if any special treatments were used.

         2.   For buildings in which all paint is to be removed,
              retain small representative areas of paint to
              provide a paint history of the building for future
              research.

         3.   An archives of the paint history of the building is
              to be maintained. This is to include any paint
              samples taken during research, samples of the new
              paint colors and the manufacturer's technical
              information.

    E.   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).

    F.   For general information on the characteristics, uses and
         problems associated with paint, see 09900-04-S.  See also
         09900-07-S for other guidelines pertaining to paint
         removal and application.

1.02 SUBMITTALS

    A.   Samples:

         1.   Under the supervision of the RHPO, test panels,
              using the appropriate cleaning methods, shall be
              done to determine the best method to remove paint.
              The "best method" shall be defined as that which
              successfully removes the paint with no, or minimal,
              damage to the masonry substrate.

         2.   Testing shall be done in unobtrusive locations on
              each building exposure. The methods used, their
              application, etc. shall be in accordance with
              manufacturer's instructions and shall duplicate
              those procedures proposed for the overall paint
              stripping process.The RHPO shall select the test
              areas and shall conduct a thorough evaluation of
              each method after paint removal is complete to
              determine the best method for the overall
              stripping.

         3.   The testing shall include an evaluation of the
              materials and techniques proposed for the
              protection of surrounding areas from the chemicals
              used to strip the paint. Especially important is
              an evaluation of the method to be used to collect
              the cleaning effluent.

         4.   A representative of the cleaning materials
              manufacturer(s) (for proprietary cleaning systems)
              shall be present during the preparation and
              application of the test areas.

1.03 PROJECT SITE CONDITIONS

    A.   Environmental Requirements:

         1.   To prevent water in the masonry from freezing, no
              paint stripping shall be done if temperatures are
              expected to fall below 40-48 degrees (F) during the stripping
              process, or within 24 hours of completing the
              stripping.  If allowed by the chemical
              manufacturer, heated rinse water may be used if
              lower temperatures are expected.

         2.   No cleaning shall be conducted during periods of
              strong winds when the chemicals may be spread to
              adjacent unprotected surfaces.

         3.   Unless otherwise recommended by the paint
              manufacturer, the ambient temperature shall be
              between 50-58 degrees (F.) and 95-98 degrees (F.)
              Do not apply paints when the temperature is expected to fall
              below 50-58 degrees(F) during the first 24 hours after application.

         4.   Do not apply any of the coats of paint in the
              direct sun.  It shall be applied only when the
              surface to be painted is in the shade and the sun
              is shining on the opposite elevation. The west
              elevation should be painted in the morning when the
              sun is shining on the east elevation; the north
              elevation should be paint around noon when the
              sun is shining on the south elevation; the east
              elevation should be painted in the afternoon when
              the sun is shining on the west elevation; and the
              south elevation should be painted late in the
              afternoon when it is in full shade.

         5.   Do not apply paint to damp surfaces, in misty or
              rainy weather, in the snow or where there is
              visible ice or frost on the surfaces.

PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.   Proprietary Chemicals:  (one of the following, or
         approved equal)

         1.   ProSoCo, Inc.
              http://www.prosoco.com/

         2.   Diedrich Technologies, Inc.
              http://www.diedrichtechnologies.com/

         3.   Hydroclean
              http://www.hydroclean.com/

         5.   Dumond Chemicals, Inc.
              http://www.dumondchemicals.com/

2.02 MATERIALS

    A.   Off-the-Shelf Chemical Paint Removers:

         1.   Semi-paste, water rinsing, nonbenzol removers such
              as Strypeeze Semi-paste, or approved equal.

              a.   Characteristic orange color.  

              b.   Will work on both latex and oil-based paints,
                   lacquers and varnishes.  

              c.   Cling well to round or vertical surfaces.
                   Form an anti-evaporative film as they dry.  

         2.   Non-flammable, heavy bodied, methylene-chloride
              based removers such as Superstrip Nonflammable, Zip
              Strip, or approved equal.

              a.   Good for interior use because they are non-flammable.  

              b.   Will soften oil-based paints, lacquers,
                   varnish and synthetic baked finishes.  

              c.   Because they are so heavy bodied they will
                   cling to vertical and irregular surfaces.  

         3.   Cornstarch or fumed silica to further thicken
              chemicals so they will adhere to vertical surfaces.

    -0R-

         One of the following proprietary paint strippers, or
         approved equal:

         1.   Sure Klean Heavy Duty Paint Stripper (ProSoCo,
              Inc.)
         2.   Sure Klean 859 Stripper (ProSoCo, Inc.)

         3.   Blok-Guard & Graffiti Control II (ProSoCo, Inc.)

         4.   Envirestrip Paint Remover (Diedrich Technologies)

         5.   505 Special Coatings Stripper (Diedrich Technologies)

         6.   606, 606X Caustic Multi-layer Paint Remover
              (Diedrich Technologies)

         7.   Heavy Duty Paint Remover (Hydroclean)

         8.   Peel Away 1,2 (Dumond Chemicals, Inc.)

    B.   Clean, potable water to remove chemical residue.
    C.   Phenolphthalein: Used to test pH of a surface after
         stripping with chemicals or any alkaline product.
         Available at some drug stores or chemical supply houses.

    D.   Clean, clear white vinegar or other appropriate
         neutralizer such as Sure Klean Restoration Cleaner
         (ProSoCo, Inc.), 101 Masonry Restorer/Cleaner (Diedrich
         Technologies), or approved equal.

    E.   Paint:  From the same manufacturer and appropriately
         suited for the conditions.

         CAUTION:  DO NOT USE A VAPOR-IMPERMEABLE PAINT ON
         SURFACES THAT MIGHT HOLD DAMP FROM GROUND OR THROUGH
         WALLS SUCH AS BADLY-PITTED BRICK CAUSED BY SANDBLASTING.

2.03 EQUIPMENT

    A.   Paint scrapers

    B.   Putty knives

    C.   Stiff bristle brushes to remove loose, flaky paint

    D.   Natural fiber cleaning brush

    E.   Synthetic fiber brush

    F.   Rollers, and/or spray equipment as appropriate and as
         recommended by paint stripper manufacturers for the
         application of their various products. Not all types of
         brushes, etc. are appropriate for all chemicals.

    G.   Plastic sheeting and duct tape may be necessary to cover
         the stripper during dwell time as it evaporates quickly.
         
    H.   Scrapers and/or pressure rinsing equipment to remove
         sludge.  

    I.   Nylon bristle brushes

    J.   Garden hose


PART 3---EXECUTION

3.01 EXAMINATION

    A.   DETERMINE THE REASON FOR PAINT REMOVAL AND WHY THE
         BUILDING WAS ORIGINALLY PAINTED.

    B.   Before work is begun on removing the existing paint film
         or otherwise preparing the surface, all flashing, gutters
         and downspouts shall be inspected and repaired or
         replaced as required.

3.02 PREPARATION

    A.   Surface Preparation: Repoint any open mortar joints to
         prevent water and chemicals from entering the wall
         structure.

3.03 ERECTION, INSTALLATION, APPLICATION

    A.   Paint Removal:

         1.   Manually scrape all loose paint and efflorescence
              using paint scrapers, putty knives or stiff bristle
              brushes. If the mortar and bricks are quite
              crumbly, use a softer brush.

         2.   Apply an off-the shelf methylene chloride-based
              paint remover (for small surface areas):

              a.   Thicken stripper with cornstarch as necessary.

              b.   Apply stripper to the surface by brush.

              c.   Cover with plastic wrap or keep misted to
                   prevent chemical from drying out before it has
                   had time to soften paint film.

              d.   When paint film is softened, rinse surface
                   completely using a garden hose or pressure
                   washing equipment. Use the lowest pressure
                   which will remove paint and paint remover -
                   usually about 300 to 500 psi, but no higher
                   than 800 psi and only on approval of RHPO.
                   HIGH PRESSURE WATER BLASTING IS NOT
                   RECOMMENDED.  Supplement rinsing as necessary
                   with a wood or plastic scrapper. Repeat if
                   required to remove all paint.  
         -OR-

              Apply a proprietary chemical paint remover (for
              large surface areas):

              a.   Apply chemical paint remover with a brush,
                   roller or appropriate spray equipment as
                   directed by manufacturer. Pressure
                   application of paint stripping materials shall
                   not be done as it tends to drive the chemicals
                   too far into the brick and mortar making it
                   impossible to remove all residue. Final
                   dilution ratio to be determined by test
                   patches done prior to removal process.

              b.   Allow the stripper to stay on the brick as
                   directed by the manufacturer and as determined
                   by test patches.

              c.   Rinse completely with clean, fresh water using
                   pressure washing equipment to remove all paint
                   and residue. Maintain water pressures as
                   recommended by chemical manufacturer and RHPO.

              d.   Apply a second coat of paint stripper if
                   necessary to remove remaining paint, again
                   following manufacturer's instructions.

              e.   Rinse completely again and apply afterwash as
                   recommended by chemical manufacturer.  

         3.   After paint has been removed, but before brick
              dries, apply neutralizer such as white vinegar, or
              a proprietary chemical neutralizer. A neutral pH
              (7 pH) should be achieved before repainting.

         4.   Allow neutralizer to stand on wall about three
              minutes before rinsing.  DO NOT LET IT DRY!

         5.   Thoroughly rinse the surface with clean, clear
              water.

         6.   Test the pH with litmus paper or phenolphthalein:

              a.   Dissolve a 2" piece of phenolphthalein in
                   denatured alcohol.  

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

         7.   Continue to neutralize the surface and test until
              there is no color change in the phenolphthalein
              solution or the litmus paper registers neutral.

    B.   Repainting:

         1.   If walls are to be repainted, allow them to dry
              completely before priming.  

         2.   Make sure all mortar joints and brick are sound,
              making any necessary repairs before priming.  

         3.   Select an acrylic or vinyl latex masonry primer or
              undercoat - one that is mildew and alkali resistant
              and made to be used on brick.  

         4.   After the primer has dried according to
              manufacturer's instructions apply two top coats of
              finish paint compatible with primer. Allow
              adequate drying time between coats.  

              1.   Primer and top coats shall be from the same
                   manufacturer and compatible with one another.

              2.   If the brick surface is badly pitted because
                   of previous sandblasting, cement-based paints
                   may be used.  Consult paint manufacturers for
                   appropriate use. See also 04211-01-P "Sealing
                   Sand-blasted Brick Masonry".

         5.   Apply paint with a brush to insure complete
              coverage. A long nap roller for use on brick may
              also be used for the top coats but great care must
              be used to ensure adequate coverage.

                         END OF SECTION
 

Last Reviewed 2015-11-24