Removing Manganese Stains From Brick Masonry
- Procedure code:
- Developed For HSPG (NPS - Southeast Regional Office)
- Brick Unit Masonry
- Last Modified:
REMOVING MANGANESE STAINS FROM BRICK MASONRY
THE CLEANING OR REMOVAL OF STAINS FROM MASONRY MAY INVOLVE THE
USE OF LIQUIDS, DETERGENTS OR SOLVENTS WHICH MAY RUN OFF ON
ADJACENT MATERIAL, DISCOLOR THE MASONRY OR DRIVE THE STAINS DEEPER
INTO POROUS MASONRY. USE THE PRODUCTS AND TECHNIQUES DESCRIBED
HERE ONLY FOR THE COMBINATIONS OF DIRT/STAIN AND MASONRY SPECIFIED.
A. This procedure includes guidance on removing brown stains
from brick masonry resulting from deposits of manganese
on the masonry surface.
B. Manganese is sometimes used in brick composition as a
C. Manganese staining is a form of efflorescence that
develops when moisture in the wall draws salts and color
from the brick composition to the surface of the masonry.
As the water evaporates, color from the manganese is left
D. Manganese stains are usually tan, brown, nearly black or
gray in color, have an oily appearance and may streak
down over the face of the brick.
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).
A. Diedrich Technologies, Inc.
CAUTION: DO NOT CLEAN MANGANESE COLORED BRICK WITH
HYDROCHLORIC ACID WITHOUT NEUTRALIZING THE ACID DURING THE
CAUTION: DO NOT USE ANY ACIDIC SOLUTIONS ON TAN, BROWN, BLACK
OR GRAY BRICK. THERE ARE SPECIAL PROPRIETARY CLEANING
COMPOUNDS AVAILABLE FOR CLEANING BRICK CONTAINING MANGANESE.
THEY SHOULD BE TESTED FOR EFFECTIVENESS PRIOR TO USE. THE
ADVICE OF THE BRICK MANUFACTURER SHOULD BE REQUESTED AND
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. Chemicals for Heavy Manganese Staining:
1. Acetic Acid (80% or stronger):
a. A colorless pungent liquid acid that is the
chief acid of vinegar and that is used
especially in synthesis (as of plastics).
b. Other chemical or common names include Vinegar
acid*. (Vinegar itself, which contains about
4% acetic acid, may be suitable for some
purposes requiring acetic acid.)
c. Potential hazards: CORROSIVE TO FLESH AND
CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS.
d. Available from chemical supply house (both
commercial and scientific), drugstore or
pharmaceutical supply distributor, grocery
store or supermarket, or hardware store.
2. Hydrogen Peroxide - 30-35% (H202):
a. An unstable compound used especially as an
oxidizing and bleaching agent, an antiseptic,
and a propellant.
b. Other chemical or common names include
Peroxide of hydrogen*; Solution of hydrogen
dioxide*; Superoxol*; (hydrogen peroxide is
commonly sold as a 3% solution; Superoxol is a
30% solution; Superoxol causes flesh burns; 3%
hydrogen peroxide does not).
c. Potential Hazards: TOXIC (when concentrated);
CORROSIVE TO FLESH; FLAMMABLE (in high
d. Available from chemical supply house,
drugstore, pharmaceutical supply distributor,
or hardware store.
Proprietary cleaner such as "Diedrich 940 Iron &
Manganese Stain Remover" (Diedrich Technologies), or
B. For Light-colored Manganese Staining:
1. Oxalic Acid (COOH)2 or (H2C2O4):
a. A poisonous strong acid that occurs in various
plants as oxalates and is used especially as a
bleaching or cleaning agent and in making
b. Other chemical or common names include
c. Potential Hazards: TOXIC; CORROSIVE TO
CONCRETE, STEEL, WOOD OR GLASS.
d. Available from chemical supply house, dry
cleaning supply distributor, drugstore or
pharmaceutical supply distributor, hardware
store, or photographic supply distributor (not
camera shop). (Often sold under a
manufacturer's brand name; the chemical name
may appear on the label.)
D. Clean, potable water
E. Clean natural fiber rags
A. Garden hose and nozzle
B. Stiff bristle brushes (no iron wire)
C. Wood scrapers
1. Provide adequate wash solutions (i.e. water, soap
and towels) before starting the job.
2. Whenever acid is used, the surface should be
thoroughly rinsed with water as soon as its action
has been adequate. Otherwise it will continue
etching the masonry even though the stain is gone.
NOTE: DO NOT TRY MORE THAN ONE TREATMENT ON A GIVEN AREA
UNLESS THE CHEMICALS USED FROM PRIOR TREATMENT HAVE BEEN
A. For Heavy Manganese Staining:
1. Mix 1 part acetic acid, 1 part hydrogen peroxide
and 6 parts water.
CAUTION: ALTHOUGH THIS SOLUTION IS VERY EFFECTIVE,
IT IS A DANGEROUS SOLUTION TO MIX AND USE. ACETIC
ACID-HYDROGEN PEROXIDE MAY ALSO BE AVAILABLE IN A
PREMIXED FORM KNOWN AS PERACETIC ACID. THIS ACID,
A TEXTILE CHEMICAL, IS ALSO DANGEROUS AND MAY BE
DIFFICULT TO PURCHASE.
2. Thoroughly wet the masonry surface with clean,
3. Brush or spray on mixture of acetic hydrogen
peroxide (see Section 3.02 A. above for mixture).
DO NOT SCRUB. The stain should disappear quickly.
4. Thoroughly rinse the wall with clean, clear water.
5. Repeat the procedure if the stains recur after a
B. For Light-colored or New Manganese Stains:
1. Mix 1 lb of oxalic acid crystals (0.45 kg) with 1
gal (3.79 L) of water.
2. Follow procedures 3.02 B.-E. above.
A. Upon completion of the masonry cleaning work, clean
window glass and spattered adjacent surfaces.
END OF SECTION