Refinishing Bronze Features
- Procedure code:
- National Capitol Region Specifications
- Metal Materials
- Last Modified:
REFINISHING BRONZE FEATURES
A. This procedure include guidance on stripping and
refinishing bronze features. Two methods are described
in Part 3 of this procedure.
B. 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).
A. Product Data:
1. Submit manufacturer s product literature and
instructions for use to Contracting Officer s
Representative for all refinishing materials.
2. Prior to commencing the refinishing operations, the
Contractor shall submit to the Contracting Officer
a written description of the entire methods and
procedures proposed for refinishing the bronze
including, but not limited to: method of
application, dilution of application, temperature
of application, length of time of surface contact,
method of rinsing surface (temperature, pressure,
and duration), repetition of procedures, etc.
1. The Contractor shall clean and refinish sample
areas on architectural bronze components included
in the work of this section as directed and for
approval by the Contracting Officer s
Representative. Locations of sample panels to be
selected by the Contracting Officer s
2. Adjust the chemical concentrations and
methodologies during test panel cleaning, as
directed by the Contracting Officer s
3. Sample areas shall be cleaned by the Contractor
using methods and materials previously submitted
and approved. Cleaning and refinishing sample
areas shall be performed in the presence of the
Contracting Officer s Representative.
4. The Contractor shall obtain written approval from
the Contracting Officer s Representative of bronze
cleaning and refinishing methods, materials,
equipment used and sample panels before proceeding
with the work of this section. For this written
approval purpose, the Contractor shall allow a
minimum of seven calendar days after completion of
sample cleaning to permit the Contracting Officer s
Representative to study the sample panels for
negative reactions. Approved sample panels shall
be marked and left unaltered. They shall be used
as the standard for similar work throughout the
A. ProSoCo, Inc.
755 Minnesota Avenue
P.O. Box 1578
Kansas City, KS 66117
800/255-4255 or 913/281-2700
B. Industrial Soap Co.
2930 Market Street
St. Louis, MI 63103
C. McIntyre Metal Maintenance
1615 South Broadway
Los Angeles, California
D. 3M Consumer Products Group
St. Paul, MN 55133-3053
612/737-6501 or 800/364-3577
E. Stanley Chemical Company
401 Berlin St.
East Berlin, CT 06023
F. Mohawk Finishing Products, Inc.
Route 30 N.
Amsterdam, NY 12010
G. Birchwood Casey
7900 Fuller Road
Eden Prairie, MN 55344
A. Architectural Bronze Stripper: Architectural bronze
stripper shall be a thixotropic solvent/alkaline paint
stripper such as Sure Klean Heavy Duty Paint Stripper
(ProSoCo, Inc.), or approved equal.
B. Non-ionic Detergent: A controlled suds, silicate
buffered, non-ionic, rinseless-type synthetic detergent,
containing no soap, alkali, solvents, abrasives, acids or
caustics such as Zyfo cleaner concentrate (Industrial
Soap Co.), or approved equal.
C. Solvent: 75% toluene + 24% acetone + 19% butal acetate.
D. Cleaner: Non-abrasive metal cleaner such as Nev-R-Dull
(McIntyre) formulated for bronze.
E. Degreasing Agent: Degreasing agent shall be
trichlorethylene or a similar solvent.
F. Patination Agent: Patination agent shall be a
commercially available conversion coating containing
Selenious Acid, Cupric Nitrate, Phosphoric Acid, Ammonium
Hydrogen Fluoride, Polyoxyethylene (12) Tridecyl Alcohol,
and Water, such as (Birchwood Casey), or approved equal.
CONSULT A SPECIALIST TO DETERMINING THE MOST APPROPRIATE
PATINATION FORMULA FOR THE METAL USED.
G. Abrasive: Abrasive shall be silicon carbide abrasive
pads such as Scotch-Brite (3M Company), or approved
H. Flattening Agent: Flattening agent for clear protective
coating shall be commercially available polyethylene
dispersion (Stan Chem Inc.), or approved equal.
I. Water shall be clean, potable, non-staining and free of
materials detrimental to all surfaces to be cleaned.
J. Cloth: Clean, cotton waste.
A. Stiff bristle brushes
B. Wet vacuum
1. Protect surrounding materials and buildings.
Products used for metal refinishing may be harmful
to masonry and glass. Any damage to materials
caused by the refinishing process is unacceptable
and shall be repaired to the satisfaction of the
Contracting Officer s Representative at no cost to
2. Provide protection from water damage to building,
structure, or building contents as required.
3. Protect trees and plants around the building from
contamination or damage. The Contractor shall be
responsible for replacing with new stock any trees,
shrubbery or grass damaged by the cleaning
B. Surface Preparation:
1. All exterior stone that may come in contact with
the cleaner shall be rinsed before, during and
after cleaning in order to avoid staining the
2. Cleaning of exterior windows shall proceed from the
top of the wall downward.
3. On the interior, mask off adjacent stone and
dissimilar metal surfaces.
3.02 ERECTION, INSTALLATION, APPLICATION
A. Remove copper sulfate from the surfaces. See 05010-23-R
for guidance. When the finish cannot be restored by
removal of sulfate formation, chemically strip to bare
metal and repatinate. NOTE: PRIOR TO CLEANING, CONSULT
A SPECIALIST TO DETERMINE AND DOCUMENT THE TYPE OF PATINA
USED AND HAVE SPECIFICATIONS DEVELOPED FOR REPATINATION.
B. Method A
1. Apply cleaner with soft cloth rubbing along grain
2. Using light to moderate uniform pressure, rub with
abrasive pad and solvent to clean surface.
a. Interior Components: Thoroughly sponge rinse
all traces of chemicals and residue with cold
water. Remove waste water as work progresses
by wet vacuum or other appropriate means. Do
not allow water to pond on floors.
b. Exterior Components: Rinse with cold water to
remove all traces of detergent and residue.
Rinse water pressure shall not exceed 100 psi
and shall be sprayed through nozzles fitted
with 15-20 degree wide tips. Nozzles shall be
held perpendicular to the surface at a working
distance of 1.5 to 2.5 feet.
4. Reapply as required to remove persistent oxidation
5. Dry surface with clean, dry cloth.
B. Method B
1. Apply a heavy coat of Architectural Bronze Stripper
with a brush.
2. Allow stripper to remain on the surface until
oxidation and copper sulfate is lifted or
dissolved. Using light to moderate uniform
pressure, rub with abrasive pad to clean surface.
a. Thoroughly sponge rinse all traces of stripper
and residue with cold water on interior
components. Remove waste water as work
progresses by wet vacuum or other appropriate
means. Do not allow water to pond on floors.
b. For exterior components, thoroughly rinse all
traces of stripper and residue with low
pressure cold water rinse. Refer to rinse
procedure specified in Section 3.02 B.3.b.
4. Reapply as required to remove persistent oxidation
5. Neutralize surface in accordance with
manufacturer s instructions.
6. Allow surface to dry thoroughly.
C. Select gentlest method - A or B which satisfactorily
cleans bronze as determined by sample panels.
D. Apply patination agent according to specialist's
specifications and in accordance with manufacturer s
instructions. Adjust concentration and dwell time in
preparation of sample panels to obtain acceptable match
with original patina as approved by RHPO.
E. Neutralize surface in accordance with manufacturer s
F. Apply clear protective coating. See 05010-08-P.
END OF SECTION