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.
A.This procedure includes guidance on cleaning metal by mild water washing with or without detergents and soft natural bristle brushes.
A. GAF Corporation
1361 Alps Road
Wayne, NJ 07470
A. Non-ionic detergent, such as "Zyfo" cleaner concentrate -a controlled suds, silicate buffered, non-ionic, rinseless-type synthetic detergent, containing no soap, free alkali, solvents, abrasives, acids, caustics or the like, "Igepal 630" (GAF Corporation) or approved equal.
B. Supplementary Materials for Bronze:
- Bronze wool, extra fine, such as that manufactured by Brillo
- Corrosion Inhibitor, Benzotriazole (BTA) such as "Cobratec" (GAF Corporation), or approved equal
C. Supplementary Materials for Cast Iron:
- 600 grit aluminum oxide paper, emery paper or fine steel wool
- Complexing agent such as "Versene", or approved equal
D. Clean, potable water
E. Toweling or rags, clean, lint-free
A. Buckets, molded rubber or plastic, such as the "Fortex" molded rubber pail - 12 or 14 quart size, or Rubbermaid
B. Washing brushes: Available from local janitorial supply houses or hardware stores
- Tampico fiber set in a hardwood block
- "Whitewash brush" - ideal for most purposes
- "Parts washing" brush - useful for small areas and crevices
C. Rubber gloves and rain gear, if desired
D. Garden hose
3.01 ERECTION, INSTALLATION, APPLICATION
A. Fill one or two buckets with about two gallons of water.
NOTE: Water washing alone will remove most common dirt and grime; however, at times supplemental materials will be needed to remove the deposits.
- For Bronze: Add BTA to wash water to make a 1 to 3% solution of BTA to water.
- For Detergent Washing: Add 1 to 3 ounces of detergent per gallon of water.
B. Beginning at the top and gradually working down, scrub the metal surface lightly with the fiber brush to remove any superficial deposits. Take care to avoid scratching or otherwise damaging the protective coating.
C. Thoroughly rinse the surface with clean, clear water.
- For Cast Iron: Rinse with 2% aqueous solution of "Versene".
D. Dry with clean, lint-free toweling or rags.
E. For tenacious mineral deposits or exudations of core material, treat locally with gentle abrasion using very fine bronze wool. Exercise great care to avoid damaging the coating and patina.