Historic Preservation - Technical Procedures
- Refinishing A Radiator
- Procedure code:
- Ohj - May 1986 And September/October 1988
- Heat Transfer
- Last Modified:
- Refinishing A Radiator
- Last Modified:
REFINISHING A RADIATOR
NOTE: REFINISHING A RADIATOR IS A TEDIOUS AND TIME-CONSUMING JOB.
IF OTHER WORK REQUIRES THE REMOVAL OF THE RADIATOR, IT IS USUALLY
BETTER TO DISCONNECT AND REMOVE THE RADIATOR AT THAT TIME FOR
REFINISHING OFF SITE. IF, HOWEVER, IT IS NOT NECESSARY TO REMOVE
THE RADIATOR, IT IS PROBABLY BETTER TO REFINISH IT IN SITU USING
ONE OF THE METHODS DESCRIBED BELOW, BECAUSE REMOVING AND
REINSTALLING A RADIATOR IS OFTEN DIFFICULT.
BEFORE UNDERTAKING ANY PROJECT INVOLVING PAINT REMOVAL, APPLICABLE
STATE AND FEDERAL LAWS ON LEAD PAINT ABATEMENT AND DISPOSAL MUST
BE CONSIDERED AND CAREFULLY FOLLOWED. STATE AND FEDERAL
REQUIREMENTS MAY AFFECT OPTIONS AVAILABLE TO OWNERS ON BOTH PAINT
REMOVAL AND REPAINTING. THESE LAWS, AND ANY REQUIREMENTS
PROHIBITING VOLATILE ORGANIC COMPOUNDS (VOCs), SHOULD BE REQUESTED
FROM THE (from Preservation Brief 28, "Painting Historic Interiors.") ENVIRONMENTAL PROTECTION AGENCY
(EPA) REGIONAL OFFICE AND/OR THE STATE OFFICE OF ENVIRONMENTAL
A. This procedure includes guidance on removing an existing
coating from a radiator and refinishing it by either
repainting, rebronzing, or polychroming.
1. Bronzing is a decorative method of painting
radiators using a mixture of bronzing liquid and
bronzing powder to achieve a metallic surface
2. Polychroming is a decorative method of painting
radiators that involves the use of two and three
color paint schemes to highlight the ornament.
B. Safety Precautions:
1. PAINT BEING REMOVED MAY CONTAIN LEAD. ALL WORKERS
MUST WEAR PROTECTIVE CLOTHING (INCLUDING HAIR),
GOGGLES, RUBBER GLOVES AND RESPIRATORS WITH HIGH
EFFICIENCY PARTICULATE AIR FILTERS (HEPA).
2. No food or drink shall be allowed near any work
station to prevent contamination from paint, paint
chips, dust or chemical removers that 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.
5. All waste material shall be collected at the end of
each work day and disposed of consistently with
local environmental regulations. It is considered
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
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 before performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
A. American Brush Co.
(Radiator Brushes and Paints)
B. Benjamin Moore, Co.
C. Glidden Coatings & Resins
D. Johnson Paint Co., Inc.
(Paints and Bronzing Liquids and Powders)
E. 3M Consumer Products Group
F. PPG Industries, Inc.
G. The Sherwin Williams Co.
A. Commercial paint remover, such as "Citristrip"
(Specialties Environmental Technologies, Inc.), "Safest
Stripper" (3M), or approved equal.
B. Zinc-rich oil-based primer such as zinc chromate or red
iron oxide-linseed oil paint:
1. Good for use on partially deteriorated surfaces.
2. Provides protection where moderately corrosive
Modern alkyd paint:
1. Should only be applied to clean, noncorroded
2. Provides protection where there are only mildly
corrosive conditions, and where normal humidity and
condensation ranges exist, i.e., a residential or
NOTE: CONSULT THE PAINT MANUFACTURER FOR APPROPRIATE
CHOICE FOR USE ON METAL.
C. Oil-based paint: Use a non-metallic flat paint.
Metallic oil-based paint (ONLY IF MAXIMUM HEAT TRANSFER
IS NOT AN IMPORTANT FACTOR)
1. Any oil-based top coat, made to be used with the
primer, may be applied as the top coats.
2. Use paint from the same manufacturer for both prime
and top coats, and make sure they are made to work
D. Bronzing Supplies:
1. Bronzing powder (the pigment): Available in a wide
range of metallic tones.
2. Bronzing liquid (the vehicle): Oil-based.
A. Radiator Brushes (American Brush Co.), or approved equal:
1. One with long handle to reach between the radiator
2. One with an offset handle for reaching behind the
3. 1-1/2" camel's hair brush
4. A wide, flat, soft brush
5. Stiff wire brush
C. Face mask
D. Drop cloths
F. Ball peen hammer
A. Before recoating, determine what role the paint or
coating is to provide.
1. If maximum heat transfer is important, use a non-
metallic coating such as a flat, black paint (a
flat finish surface radiates heat better than a
NOTE: OIL PAINTS GENERALLY DO NOT REDUCE HEAT
TRANSMISSION IN A RADIATOR AND ARE SUITABLE FOR USE
WHEN MAXIMUM HEAT TRANSFER IS AN ISSUE.
NOTE: AVOID USING METAL BRONZE PAINTS OR ANY
PAINTS CONTAINING METAL PARTICLES. THESE TEND TO
REDUCE HEAT TRANSMISSION IN A RADIATOR.
2. If aesthetics are important and potential heat loss
is acceptable, bronzing may be a suitable
3.02 ERECTION, INSTALLATION, APPLICATION
A. Strip existing coating from the radiator.
CAUTION: PAINT MAY CONTAIN LEAD. FOLLOW ALL SAFETY
REGULATIONS REQUIRED BY STATE AND FEDERAL LAWS ON LEAD
PAINT ABATEMENT AND DISPOSAL.
1. Mechanical Method: This method is typically the
most commonly used and the most successful.
a. Knock off loose paint and scale using a stiff
wire brush. Special radiator brushes are also
available (see Part 2 above).
b. Tap the radiator repeatedly with a ball peen
hammer to loosen the paint bond on tougher
c. Vigorously brush the radiator again with a
stiff wire brush to remove remaining paint. A
wire brush on a rotating drill may be used if
the worker is protected and working in an
2. Chemical Method: This method is typically time-
consuming and messy.
a. Apply a NON-methylene chloride paint stripper
using a stiff bristle brush.
b. Cover the stripper with strips of plastic wrap
to prevent the solvents in the stripper from
c. Allow stripper to remain on the surface for
length of time as recommended by manufacturer.
d. Remove plastic wrap and remove sludge with
small chisels and brushes.
e. Rinse the surface with mineral spirits and
allow to dry.
3. Heat Method: This method is not very effective in
removing coatings from a radiator. Heat from the
heat gun gets absorbed into the cast iron before it
has time to soften the paint.
4. Remove the radiators and have them stripped off-
site by immersion-tank stripping or sandblasting.
NOTE: REMOVAL AND REINSTALLATION OF A RADIATOR IS
VERY DIFFICULT. THIS METHOD SHOULD ONLY BE USED IF
REMOVAL OF THE RADIATOR IS REQUIRED FOR OTHER
a. Drain the hot water system and disconnect the
b. Remove the radiator and send off-site for
stripping and recoating.
B. Refinish Radiator:
CAUTION: DO NOT USE WATER-BASED PAINTS ON CAST
IRON. THEY MAY CAUSE THE METAL TO RUST.
1. Prime paint the radiator using a brush for
complete even coverage.
2. Brush apply two top coats of the selected oil-
a. Prime paint the radiator using spray auto-body
paint. Auto-body paint is appropriate for
1) It can withstand radiator heat.
2) It is sandable, enabling one to hide
small imperfections in the metal.
3) It is available in light grey and other
colors suitable as a base for bronzing.
b. Sand the entire surface with fine-grit
c. Brush sandpaper dust from the surface using a
stiff bristle brush.
d. Mix bronze metallic paint in a bucket. Mix
1/2 lb. bronzing powder with 2 cups bronzing
liquid. Add the powder to the liquid to
achieve a paint the consistency of cream.
NOTE: 1 QT. BRONZING LIQUID TYPICALLY COVERS
e. Brush mixture onto the radiator carefully
using several soft bristle brushes as required
(see brushes under Part 2 above).
NOTE: BE SURE TO USE SOFT BRISTLE BRUSHES. A
STIFF BRUSH MAY INHIBIT ACHIEVING A SMOOTH
METALLIC FINISH WHEN APPLYING THE BRONZE
PAINT. ALWAYS BRUSH IN THE SAME DIRECTION.
3. Polychroming: Typically used on ornamental
radiators for highlighting special ornamental
a. Prime paint and sand the radiator (see Section
3.02 B. 2. a-c above).
b. Using brushes, paint the entire radiator the
color desired for the ornament and allow to
c. When dry, paint the entire radiator the color
desired for the background.
d. While the second coat of paint is still tacky,
wipe a clean cloth or sponge over the ornament
ONLY to expose the paint color below.
e. The ornament may also be hand painted if
END OF SECTION