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Historic Preservation - Technical Procedures

Spectitle:

Removing Unknown Stains From Marble Using A Poultice

Procedure code:

0445502R

Source:

Outdoor Sculpture Manual - Center For Public Buildings

Division:

Masonry

Section:

Marble

Last Modified:

07/02/2012

Details:

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.


PART 1---GENERAL

1.01 SUMMARY

    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
         poultice.

    D.   When the poultice has dried, it is scraped and brushed
         away.

    E.   Safety Precautions:

         1.   DO NOT save unused portions of stain-removal
              materials.

         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
         poultices.

         1.   Health hazards associated with the improper
              utilization of organic solvents.

              a.   Benzene is a carcinogen.

              b.   Methylene chloride is dangerous to people with
                   heart problems.

              c.   Carbon tetrachloride may cause liver or kidney
                   failure.

              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
                   flammable substance.

         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
              staining.

         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.


PART 2---PRODUCTS

2.01 MATERIALS

    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
         be used

         -OR-

         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
              propellant.

         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
              does not).

         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
              concentration).

         4.   Available from chemical supply house, drugstore,
              pharmaceutical supply distributor, or hardware
              store.

    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

2.02 EQUIPMENT

    A.   Glass or ceramic container for mixing the solution

    B.   Wooden utensil for stirring the ingredients

    C.   Wood or plastic spatula

    D.   Masking tape


PART 3---EXECUTION

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
              mineral water.

         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
              peroxide.

         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
              be treated).

         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
              water.

         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
              necessary.

    B.   For Dingy Marble:

         1.   Thoroughly rinse the area to be treated with
              mineral water.

         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
              cleanliness.

                         END OF SECTION
 


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