Cleaning Exterior Copper Components
- Procedure code:
- Developed For Hspg (Nps - Sero)
- Ornamental Copper
- Last Modified:
CLEANING EXTERIOR COPPER COMPONENTS
A. This procedure includes guidance on cleaning exterior
copper architectural elements that are dirty, soiled, or
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. For additional information on the characteristics, uses
and problems associated with copper, see 05015-01-S.
1.02 SYSTEM DESCRIPTION
A. Ornamental elements of copper are formed of very thin
copper sheets. They should be in good condition, without
any signs of surface dirt, debris, soiling, or
NOTE: Chemical products are sometimes sold under a common
name. This usually means that the substance is not as pure as
the same chemical sold under its chemical name. The grade of
purity of common name substances, however, is usually adequate
for stain removal work, and these products should be purchased
when available, as they tend to be less expensive. Common
names are indicated below by an asterisk (*).
A. Copper Sulfate (CuSO45H20):
1. A sulfate of copper especially the normal sulfate
that is white in the anhydrous form but blue in the
crystalline hydrous form and that is often used as
an algicide and fungicide.
2. Other chemical or common names include Cupric
Sulfate; Blue stone*; Blue vitriol*; Roman
3. Potential Hazards: TOXIC.
4. Available from chemical supply house, drugstore or
pharmaceutical supply distributor, garden and lawn
supply center, hardware store, swimming pool supply
distributor, or water and sanitation supply
B. Nitric Acid (HNO3):
1. A corrosive liquid inorganic acid used especially
as an oxidizing agent, in nitrations, and in making
organic compounds such as fertilizers, explosives
2. Potential Hazards: CORROSIVE TO FLESH; CORROSIVE
TO CONCRETE, STEEL, WOOD OR GLASS.
3. Available from chemical supply house or hardware
C. Clean, potable water
A. Cellulose sponge mop or similar applicator
B. Clean soft wiping cloths
C. Heavy gloves and protective gear
A. Mix 4 ounces of copper sulfate, 1/2 gallon of lukewarm
water and 1/8 ounce of nitric acid.
NOTE: ABRASIVE AGENTS ARE NOT TO BE USED.
B. Apply the solution to the copper surface using a
cellulose sponge mop or similar hand applicator.
CAUTION: AVOID APPLYING CLEANING SOLUTION TO METAL IN
DIRECT SUN, AS IT BECOMES VERY HOT, AND THE DETERGENT OR
SOAP SOLUTION WILL DRY IN STREAKS BEFORE IT IS POSSIBLE
TO RINSE IT OFF. THESE STREAKS CAN VERY EASILY BECOME
PERMANENT AND CANNOT BE REMOVED WITHOUT ABRASION.
C. Thoroughly rinse the surface with clean, clear water and
dry with clean, soft cloths. Repeat the process as
required to achieve the desired level of cleanliness.
END OF SECTION