U.S. General Services Administration
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.
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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 SMOKE STAINS FROM BRICK MAS= ONRY
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.
PART 1–GENERAL
1.01 SUMMARY
A. This procedure includes guidance on removing smoke stains from brick masonry.
B. See 01100-07-S for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections:
- Safety Precautions
- Historic Structures Precaution= s
- Submittals
- Quality Assurance
- Delivery, Storage and Handling=
- Project/Site Conditions
- Sequencing and Scheduling
- 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).=0CPART 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. Scouring powder containing bleach
-OR-
Alkali detergent or commercial emulsifying agent.
B. Trichloroethylene (highly refined solvent):
CAUTION: TRICHLOROETHYLENE IS HIGHLY TOXIC AND MAY REACT WITH STRONG ALKALIS SUCH AS FRESH CONCRE= TE TO FORM DANGEROUS GASES.
- Other chemical or common names include Ethinyl trichloride.
- Potential Hazards: TOXIC
- Available from automotive supply distributor, chemical supply house (both commercial and scientific), dry cleaning supply distributor, paint store, photographic supply distributor (not camera shop), or printer’s supply distributor.
C. Filler material such as diatomaceous earth or powdered talc
D. Clean, potable water
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. Stiff bristle brush
E. Masking tape
PART 3–EXECUTION
3.01 ERECTION, INSTALLATION, APPLICATION
NOTE: WHEN CLEANING, AVOID OVERCLEANING. AIM FOR ACHIEVING 85% CLEAN. MOST DAMAGE OCCURS WHEN ATTEMPTING TO CLEAN THE LAST 15%.
NOTE: TEST CLEAN A SMALL AREA BEFORE ATTEMPTING TO CLEAN LARGE AREAS.
A. Scrub the affected area with a stiff bristle brush and scouring powder containing bleach. -OR- Brush or spray apply an alkali detergent or commercial emulsifying agent.
B. For small stubborn stains, apply a poultice of trichloroethylene and inert filler material.
- Thoroughly rinse the area to be treated with mineral water.
- Mix the liquid solution to be used in a glass or ceramic bowl.
- Thoroughly moisten the stained surface with this liquid. Be sure to dampen well beyond the stain.
- 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).
- 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 masonry.=
- Check the coating for air pockets or voids.
- Cover the poultice with plastic sheeting and seal with masking tape.
- Let set for 48 hours (unless otherwise specified).
- After set period, dampen the poultice with mineral water.
- Remove the poultice with a wooden or plastic spatula to avoid scratching the surface.
- Thoroughly rinse the cleaned area with mineral water, blot with clean towels and allow the surface to dry.
- Repeat the process as necessary to remove any remaining residue until a desired level of cleanliness is achieved.