Removing Unknown Stains From Marble Using A Poultice
REMOVING UNKNOWN STAINS FROM MARBLE USING A POULTICE
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 preparing a general
poultice for removing unknown stains from marble. For
removal of a specific stain type, see the appropriate
procedure(s) as listed below:
1. Copper/Bronze Stains: See 04400-07-R.
2. Greasy Smudges: See 04455-10-R.
3. Oil and Fat Stains: See 04455-11-R.
4. Etch Marks: See 04455-15-R.
5. Ink and Dye Stains: See 04455-18-R.
6. Organic Stains: See 04455-14-R.
7. Linseed Oil Paints: See 04455-12-R.
8. Latex and Acrylic Paints: See 04455-13-R.
9. Rust Stains: See 04400-06-R.
10. Iodine Stains: See 04455-16-R.
11. Urine Stains: See 04455-17-R.
B. A poultice is usually made by adding a solvent or
chemical cleaning agent to water and blended with an
inert filler to make a smooth paste. The paste is then
applied over the stain using a trowel or spatula.
C. The liquid portion of the paste migrates into the stone
where it dissolves some of the staining material. Then
the liquid gradually moves back beyond the stone surface
and into the poultice, from which it evaporates, leaving
its burden of dissolved staining material in the
D. When the poultice has dried, it is scraped and brushed
E. Safety Precautions:
1. DO NOT save unused portions of stain-removal
2. DO NOT store any chemicals in unmarked containers.
3. Excellent ventilation should be provided wherever
any solvent is used.
4. 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 stone even though the stain is gone.
F. Historic Structures Precautions: Users should be aware
of the nature and dangers associated with all techniques
used in their workplace. The following notes are general
concerns and precautions when using solvent based
1. Health hazards associated with the improper
utilization of organic solvents.
a. Benzene is a carcinogen.
b. Methylene chloride is dangerous to people with
c. Carbon tetrachloride may cause liver or kidney
d. Methylhydrate may cause intoxication followed
by blindness or even death.
e. Acetone should never be used in a closed area.
The work place should be well ventilated and
away from flames and sparks as it is a highly
2. The cost of organic solvents is high compared to
other cleaning methods.
3. There is a danger, when using organic solvents, of
spreading the stain into adjoining masonry. Areas
adjacent to the stain should be adequately
protected and cleaning agents to be applied to the
stain should be administered starting at the bottom
of the stain and working upward to avoid further
4. Do not use solvents containing color agents or oil
on stone. Avoid these solvents: turpentine,
leaded kerosene and gasoline.
G. For general information on the characteristics, uses and
problems associated with marble, see 04455-01-S.
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. "Liquid cleaner" - See individual procedures listed under
Section 1.01 Summary for specific products/chemicals to
Where none is specified, use laundry bleach, a 6%
solution of hydrogen peroxide, or detergent such as
"Tide", or approved equal.
Hydrogen Peroxide (H202):
1. An unstable compound used especially as an
oxidizing and bleaching agent, an antiseptic, and a
2. 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
3. Potential Hazards: TOXIC (when concentrated);
CORROSIVE TO FLESH (gasoline, kerosene and mineral
spirits are each a mixture of compounds from
petroleum, all of which fall within a specified
range of properties); FLAMMABLE (in high
4. Available from chemical supply house, drugstore,
pharmaceutical supply distributor, or hardware
B. White absorbent material (molding plaster, untreated
white flour, white tissue, paper towels, powdered chalk,
talc, fullers earth or laundry whiting).
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
3.01 ERECTION, INSTALLATION, APPLICATION
NOTE: For removal of a specific stain type, see the
appropriate procedure(s) as listed in Section 1.01 Summary.
A. For unknown stains, try the following:
NOTE: DO NOT USE BLEACH ON DARK COLORED STONES AS THIS
WILL CAUSE THE STONE TO LIGHTEN.
1. Thoroughly rinse the area to be treated with
2. Mix the liquid solution to be used in a glass or
ceramic bowl. Use liquid solution as called for in
each specific stain removal procedure (see Section
1.01 Summary) -or- 6% solution of hydrogen
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. For Dingy Marble:
1. Thoroughly rinse the area to be treated with
2. Add enough water to "Tide" powdered laundry
detergent to achieve a very thick paste the
consistency of pancake batter.
NOTE: NEVER ADD THE POWDER TO THE WATER. ALWAYS
ADD THE WATER TO THE POWDER.
3. Spread the paste over the affected area with a wood
or plastic spatula to a thickness of about 1/4".
4. Cover the area with plastic sheeting and allow to
soak for three days.
5. Remove the plastic and allow the poultice to dry.
6. Remove the dried poultice with a wood or plastic
spatula and a stiff bristle brush.
7. Thoroughly rinse the surface with clean, clear
water and allow to dry.
8. Repeat as necessary to achieve the desired level of
END OF SECTION