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.
- This standard includes guidance on making job-prepared hypochlorite for use in removing specific stains from concrete. It is recommended for use in removal of the following stains:
- Beverage Stains: See "Removing Beverage Stains from Concrete".
- Fire, Smoke, Soot, Pitch and Wood Tar Stains: See "Removing Fire, Smoke, Soot, Pitch And Wood Tar Stains From Concrete".
- Urine Stains: See "Poulticing Urine Stains From Concrete".
- Wood Stains: See "Removing Wood Stains From Concrete".
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 (*).
- Calcium Hypochlorite (CaCl2O2):
- A white powder used especially as a bleaching agent and disinfectant.
- Other chemical or common names include Chlorinated calcium oxide; Bleaching powder*; Calcium oxymuriate*; Chloride of lime*; Chlorinated lime*; Hypochlorite of lime*; Oxymuriate of lime*.
- Potential Hazards: Caustic to flesh; flammable (when in contact with organic solvents); toxic from contact, inhalation & ingestion
- Available from chemical supply house, dry cleaning supply distributor, drugstore or pharmaceutical supply distributor, janitorial supply distributor, swimming pool supply distributor, or water and sanitation supply distributor.
- Trisodium Phosphate:
- Other chemical or common names include Tribasic sodium phosphate; Trisodium orthophosphate; Sodium orthophosphate; TSP*; Phosphate of soda*.
- Potential Hazards: Caustic to flesh.
- Available from chemical supply distributor, supermarket, grocery, or hardware store.
- Clean, potable water
- Enameled shallow pan
- Rubber or plastic buckets or stoneware jar
3.01 ERECTION, INSTALLATION, APPLICATION
- Dissolve 2 pounds of sodium orthophosphate crystals in 1 gallon of hot water in a rubber or plastic bucket.
- In a shallow enamel pan, place 12 ounces by weight of calcium hypochlorite. Add water slowly and mix to a paste while mashing the lumps.
- Pour the two solutions into another rubber or plastic bucket or into a stoneware jar and mix in enough water to make a total of 2 gallons of solution.
- Stir well, cover and allow the lime to settle.
- Carefully pour off the liquid for use, leaving the solids behind. The liquid can be siphoned off, but do not start the suction by mouth.