Historic Preservation - Technical Procedures
- Chemically Removing Paint From And Repainting Brick Masonry
- Procedure code:
- Developed For HSPG(NPS - Southeast Regional Office)
- Brick Unit Masonry
- Last Modified:
- Chemically Removing Paint From And Repainting Brick Masonry
- Last Modified:
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")
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
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
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
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. 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
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.
A. Proprietary Chemicals: (one of the following, or
1. ProSoCo, Inc.
2. Diedrich Technologies, Inc.
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.
One of the following proprietary paint strippers, or
1. Sure Klean Heavy Duty Paint Stripper (ProSoCo,
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
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.
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
I. Nylon bristle brushes
J. Garden hose
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.
A. Surface Preparation: Repoint any open mortar joints to
prevent water and chemicals from entering the wall
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.
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
6. Test the pH with litmus paper or phenolphthalein:
a. Dissolve a 2" piece of phenolphthalein in
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.
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