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.
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.
- This procedure includes guidance on preparing a general paste for removing unknown stains from marble. This method of application is useful for applying solvent or bleaching chemicals to graffiti or stains on horizontal stone surfaces. For removal of a specific stain type, see the appropriate procedure(s) as listed below:
- Copper/Bronze Stains: See 04400-07-R.
- Greasy Smudges: See 04455-10-R.
- Oil and Fat Stains: See 04455-11-R.
- Etch Marks: See 04455-15-R.
- Ink and Dye Stains: See 04455-18-R.
- Organic Stains: See 04455-14-R.
- Linseed Oil Paints: See 04455-12-R.
- Latex and Acrylic Paints: See 04455-13-R.
- Rust Stains: See 04400-06-R.
- Iodine Stains: See 04455-16-R.
- Urine Stains: See 04455-17-R.
- 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 Precautions
- 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).
- 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 (*).
- Solvent such as trichloroethylene (highly refined solvent): CAUTION: TRICHLOROETHYLENE IS HIGHLY TOXIC AND MAY REACT WITH STRONG ALKALIS SUCH AS FRESH CONCRETE 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.
- Molding plaster
- Mineral water
- Clean, lint-free cloths
- Waterproof container for mixing the paste
- Wooden spoon or spatula
- Wooden scraper (for removing the mold)
3.01 ERECTION, INSTALLATION, APPLICATION
- Pour a moderate amount of mineral water into the container.
- Add a small amount of molding plaster to the water.
- Stir the mixture, continue adding plaster and stirring until the solution has the consistency of toothpaste.
- Mold the paste like a bird's nest and place it on the stain. Be sure the mold covers the entire stain and parts of the unsoiled stone surrounding the entire stain.
- Allow the nest to dry (approximately 30 minutes).
- Pour some solvent into the nest and allow to set for about three hours.
- After the set period, remove the mold with a wooden scraper (to avoid scratching the surface).
- Thoroughly rinse the surface thoroughly with mineral water.
- Blot the surface with clean, lint-free cloths and allow it to dry completely.
- If residual staining remains, repeat the treatment until the entire stain has been removed.