Historic Preservation - Technical Procedures
- Removing Oil And Fat Stains From Marble
- Procedure code:
- Outdoor Sculpture Manual - Center For Public Buildings
- Last Modified:
- Removing Oil And Fat Stains From Marble
- Last Modified:
REMOVING OIL AND FAT STAINS FROM MARBLE
THE CLEANING OR REMOVAL OF STAINS FROM STONE MAY INVOLVE THE USE
OF LIQUIDS, DETERGENTS OR SOLVENTS WHICH MAY RUN OFF ON ADJACENT
MATERIAL, DISCOLOR THE STONE OR DRIVE THE STAINS DEEPER INTO POROUS
STONES. USE THE PRODUCTS AND TECHNIQUES DESCRIBED HERE ONLY FOR
THE COMBINATIONS OF DIRT/STAIN AND STONE SPECIFIED.
A. This procedure includes guidance on poulticing marble
stained with oil and fat containing substances such as
oil based paints, lipstick, butter, cream, milk, peanut
butter, hand lotions, mustard and deposits bound to the
surface by or consisting entirely of oils, grease and/or
B. Oil stains are usually light brown or yellow in color.
C. Most oil based products are composed of some material,
often pigmented, suspended in an oily vehicle. When such
a product is applied to a surface, the oil tends to
penetrate into porous substrates such as masonry. The
pigmented matrix may rest on the surface, while the oil
is absorbed into the stone, generally causing a darkening
D. Poulticing is the most effective means of removing oil
and fat stains from marble. A solvent is used to
dissolve the oil, and a medium is applied to the surface
which absorbs the oil, drawing it to the surface and into
the poulticing medium as it dries.
1. Stain removal by conventional washing is usually
impossible. The pigmented matrix may be removed by
scraping or washing; however, the dark oil stains
are usually quite apparent, especially on white or
light colored stone.
2. Abrasive cleaning techniques are INAPPROPRIATE and
NOT RECOMMENDED, as they result in excessive loss
of surface material and altered texture.
Furthermore, abrasive cleaning will not remove
deeply penetrated oil staining.
3. Steam cleaning is also INAPPROPRIATE and NOT
RECOMMENDED for this type of stain removal as the
steam heat reduces the viscosity of the oil and
drives it deeper into the stone, spreading the
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).
F. For additional information on poulticing, see 04455-02-R.
G. For general information on the characteristics, uses and
problems associated with marble, see 04455-01-S.
A. ProSoCo, Inc.
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. Acetone (C3H6O):
1. A volatile fragrant flammable liquid ketone used
chiefly as a solvent and in organic synthesis and
found abnormally in urine.
2. Other chemical or common names include Dimethyl
3. Potential Hazards: VOLATILE AND FLAMMABLE SOLVENT
4. Available from chemical supply house or hardware
1. A petroleum distillate that is used especially as a
paint or varnish thinner.
2. Other chemical or common names include Benzine*
(not Benzene); Naphtha*; Petroleum spirits*;
3. Potential Hazards: TOXIC AND FLAMMABLE.
4. Safety Precautions:
a. AVOID REPEATED OR PROLONGED SKIN CONTACT.
b. ALWAYS wear rubber gloves when handling
c. If any chemical is splashed onto the skin,
wash immediately with soap and water.
5. Available from construction specialties
distributor, hardware store, paint store, or
printer's supply distributor.
Commercial cleaner such as "Stand Off Oil and Grease Stain
Remover" (ProSoCo, Inc.), or approved equal.
B. White absorbent material (molding plaster, untreated
white flour, white tissue, paper towels, powdered chalk,
talc, baking powder, baking soda, fullers earth or
laundry whiting), or a commercial absorbent material such
"Stand Off Poultice Powder"(Prosoco), or approved equal.
C. Mineral water
D. Plastic sheeting
E. Clean dry towels for blotting the area after treatment
A. Glass or ceramic container for mixing the solution
B. Wooden utensil for stirring the ingredients
C. Wood or plastic spatula
D. Masking tape
A. Examine the marble surface CAREFULLY to determine the
cause of staining before proceeding with any cleaning
3.02 ERECTION, INSTALLATION, APPLICATION
NOTE: BEGIN CLEANING BY USING THE GENTLEST METHOD POSSIBLE.
TEST CLEAN A SMALL AREA BEFORE ATTEMPTING TO CLEAN LARGE AREAS
TO DETERMINE APPROPRIATE DWELL TIMES AND NUMBER OF
APPLICATIONS NECESSARY TO ADEQUATELY REMOVE THE STAIN.
A. Apply a poultice:
1. Rinse the area to be treated with mineral water.
2. Mix the acetone or mineral spirits in a glass or
ceramic bowl. Use an amount adequate to fully
cover the affected area.
3. Thoroughly moisten the stained surface with this
liquid. Be sure to dampen well beyond the stain.
4. Mix the remaining liquid with the white absorbent
material to form a paste the consistency of oatmeal
or cake icing. (Approximately one pound of paste
is needed for every square foot of surface area to
5. Using a wooden or plastic spatula, apply the paste
to the stained surface in layers no more than 1/4
inch thick. The poultice should extend well beyond
the stain to prevent forcing the stain into
previously clean stone.
6. Check the coating for air pockets or voids.
7. Cover the poultice with plastic sheeting and seal
with masking tape.
8. Let set for 48 hours (unless otherwise specified).
9. After set period, dampen the poultice with mineral
10. Remove the poultice with a wooden or plastic
spatula to avoid scratching the surface.
11. Again, thoroughly rinse the cleaned area with
mineral water, blot with clean towels and allow the
surface to dry.
12. Once the surface has dried completely, check for
remaining residue and repeat the treatment if
B. Apply a commercial cleaner following manufacturer's
END OF SECTION