Technical Procedures Disclaimer
Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.
We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.
REMOVING IODINE 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 removing iodine
stains from marble with an alcohol poultice.
B. 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).
C. For additional information on poulticing, see 04455-02-R.
D. For general information on the characteristics, uses and
problems associated with marble, see 04455-01-S.
NOTE: When the common name of a chemical is used on the
label, it is usually a sign that the substance is not as pure
as the same chemical sold under its chemical name. However,
the grade of purity of the common-name substance is almost
certain to be adequate for stain removal work, and because it
is likely to be less expensive, the common-name product should
be purchased when available. Common names are indicated by an
A. Denatured Alcohol:
1. Other chemical or common names include Methylated
2. Potential hazards: TOXIC AND FLAMMABLE.
3. Available from hardware store, paint store or
printer's supply distributor.
4. Denatured alcohol, which carries no liquor tax,
should be a satisfactory substitute for ethyl
alcohol for stain removing purposes.
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
A. Examine the marble surface CAREFULLY to determine the
cause of staining before proceeding with any cleaning
3.02 ERECTION, INSTALLATION, APPLICATION
A. Iodine stains will normally disappear without treatment.
B. For quick removal, apply a poultice of denatured alcohol
1. Thoroughly rinse the area to be treated with
2. Pour the denatured alcohol in a glass or ceramic
bowl. Use an amount adequate to fully cover the
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, rinse the cleaned area with mineral water,
blot with clean towels and allow the surface to
12. Once the surface has dried completely, check for
remaining residue and repeat the treatment if