Cleaning Masonry Using Ammonium Fluoride Treatment
- Procedure code:
- Outdoor Sculpture Manual - Center For Public Buildings
- Masonry Cleaning
- Last Modified:
CLEANING MASONRY USING AMMONIUM FLUORIDE TREATMENT
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 the removal of dirt
from masonry by poulticing with an ammonium fluoride
B. Safety Precautions:
1. DO NOT save unused portions of stain-removal
2. DO NOT store any chemicals in unmarked containers.
3. EXCELLENT VENTILATION MUST BE PROVIDED WHEREVER ANY
SOLVENT IS USED. USE RESPIRATORS WITH SOLVENT
4. No use of organic solvents indoors should be
allowed without substantial air movement. Use only
spark-proof fans near operations involving
5. Provide adequate clothing and protective gear where
the chemicals are indicated to be dangerous.
6. Have available antidote and accident treatment
chemicals where noted.
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 prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
D. For additional information on poulticing, see 04455-02-R.
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. Ammonium fluoride:
CAUTION: USE EXTREME CAUTION WITH THIS MATERIAL.
1. Other chemical or common names include Ammonium
bifluoride; Ammonium hydrogen fluoride.
2. Potential Hazards: TOXIC; CORROSIVE TO FLESH;
CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS;
3. Available from chemical supply house or dairy
B. White absorbent material such as molding plaster,
untreated white flour, powdered chalk, talc, fullers
C. Mineral water
A. Glass or ceramic bowl for mixing ingredients
B. Wooden utensil for stirring the ingredients
C. Wood or plastic spatula
D. Brushes - one fine stencil brush, and a natural bristle
A. Protection: Provide adequate wash solutions (i.e. water,
soap and towels) before starting the job.
3.02 ERECTION, INSTALLATION, APPLICATION
NOTE: DO NOT TRY MORE THAN ONE TREATMENT ON A GIVEN AREA
UNLESS THE CHEMICALS USED FROM PRIOR TREATMENT HAVE BEEN
A. Mix ammonium fluoride with one of the white absorbent
materials listed in Section 2.02 above to form a thick
B. Thoroughly wet the surface to be treated with mineral
C. Apply the paste with a fine stencil brush (be sure to
eliminate any air pockets or voids created in the
D. Let the paste dry for twenty minutes.
E. Carefully remove the paste with a wood or plastic
spatula, or a stiff natural bristle brush.
F. Thoroughly rinse the surface with clean, cool mineral
water and allow to dry.
G. Repeat as necessary to achieve the desired level of
END OF SECTION