Historic Preservation - Technical Procedures
Removing Paint From Bronze
National Capitol Region Specifications
Removing Paint From Bronze
REMOVING PAINT FROM BRONZE
A. This procedure includes guidance on removing paint from
bronze features and refinishing using an oxidizing agent
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).
C. Cleaning and refinishing bronze is highly specialized and
should be conducted under the supervision of a metals
conservator. All chemicals and their application should
be approved prior to use by the metals conservator to
ensure protection of historic metals.
A. Leo Silfen, Inc.
Industrial Chemical Division
525 Fourth Avenue
Mt. Vernon, New York
B. McIntyre Metal Maintenance
1615 South Broadway
Los Angeles, California
C. Enthone Corporation
New Haven, CT
D. Stanley Chemical
401 Berlin Street
East Berlin, CT 06023
A. Metal Cleaner: Suitable cleaners are:
1. Marine Type Metal Polish Formula 90 (Industrial
Chemical Division, Leo Silfen, Inc.), or approved
2. McIntyre Metal Cleaner (McIntyre Metal
Maintenance), or approved equal.
B. Standard Solvent:
1. A mixture of 75% toluene, 24% acetone, and 1% butyl
acetate. (Available from chemical supply firms.)
2. As an alternate, solvents normally used for
thinning nitro-cellulose lacquers, such as "DuPont
Lacquer Solvent No. 3661-S" (for use in mid-
temperature, 50 to 80 F).
C. Inhibitor/Cleaner: 1% Benzotriazole solution in warm
water (40 grams Benzotriazole/gallon of water).
D. Paint/Lacquer Remover: Methylene chloride flush-away
type remover, such as "S-26", (Enthone Corporation), or
E. Mild Soap: Ivory or a mild detergent with pH of
F. Clear Coating: Acrylic lacquer containing acrylic ester
resins dissolved in toluene with benzotriazole as
corrosion inhibitor, such as "Incralac", (Stanley
Chemical), or approved equal.
G. Abrasive: Silicon carbide abrasive pads, such as
"Scotch-Brite", (3M Company), or standard commercially
available pumice stone; or stainless steel wool. DO NOT
USE STEEL WOOL, WHICH MAY PROMOTE DISCOLORATION OF THE
H. Oxidizing Agent: Aluminum chloride or liquid sulfur.
I. Cloth: Clean cotton waste.
A. Protection: Protect all masonry surfaces immediately
adjacent to or below the area to be cleaned by covering
with polyethylene sheeting.
3.02 ERECTION, INSTALLATION, APPLICATION
A. Remove old paint using paint remover applied with a
cotton cloth wiped along the grain of the metal.
B. Allow the remover to stand on the paint for several
minutes, then remove by wiping with a cotton cloth or by
flushing with water. Several applications of the
stripper may be necessary in order to remove all traces
of the paint from the metal.
C. Follow the stripping operation with an application of
metal cleaner on a soft cloth, rubbing along the grain of
the metal. Clean surface dirt and grease only; do not
rub down to bright metal. Rinse thoroughly with clear
D. Persistent stains or badly corroded areas may be cleaned
using an abrasive and standard solvent under the
direction of a metals conservator. All cleaner residue
should be removed by washing the metal surface at least
twice with a standard solvent.
E. See 05010-08-P for guidance on lacquering bronze.
F. See 05010-22-R for guidance on cleaning and oiling
statuary bronze features.
END OF SECTION