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 COPPER, SILVER AND NICKEL STAINS FROM CERAMIC TILE
THE CLEANING OR REMOVAL OF STAINS FROM TILE MAY INVOLVE THE USE OF LIQUIDS, DETERGENTS OR SOLVENTS WHICH MAY RUN OFF ON ADJACENT MATERIAL, DISCOLOR THE TILE OR DRIVE THE STAINS DEEPER INTO POROUS TILE. USE THE PRODUCTS AND TECHNIQUES DESCRIBED HERE ONLY FOR THE COMBINATIONS OF DIRT/STAIN AND TILE SPECIFIED.
A. This procedure includes guidance on removing copper, silver and nickel stains from ceramic tile.
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 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).
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. Household ammonia: CAUTION: DO NOT MIX AMMONIA WITH CHLORINE BLEACHES, A POISONOUS GAS WILL RESULT! DO NOT USE BLEACH ON BIRD DROPPINGS.
- Other chemical or common names include Ammonium Hydroxide; Ammonia water*; Aqua ammonia*.
- Potential hazards: TOXIC; MAY IRRITATE THE EYES.
- Available from chemical supply house, grocery store or pharmaceutical supply distributor, or hardware store.
B. Nitric acid (HNO3):
- A corrosive liquid inorganic acid used especially as an oxidizing agent, in nitrations, and in making organic compounds such as fertilizers, explosives and dyes.
- Potential Hazards: CORROSIVE TO FLESH; CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS.
- Available from chemical supply house or hardware store.
C. Clean, potable water
A. Clean natural fiber rags, or sponges
B. Stiff bristle brushes (no iron wire)
A. Examine the ceramic tile surface carefully to determine the type and cause of staining before proceeding with any cleaning operation.
3.02 ERECTION, INSTALLATION, APPLICATION
A. For Copper Metal Stains: NOTE: DO NOT USE THIS TREATMENT ON GLAZED TILE.
- Wash the surface using a clean cloth or sponge soaked with a 10% nitric acid solution.
- Rinse the treated area immediately with clean, clear water and allow to dry.
B. For Silver and Nickel Stains:
- Wash the affected area using a clean cloth or sponge soaked with household ammonia.
- Rinse the treated surface with clean, clear water and allow to dry.
- Repeat the process as necessary to achieve the desired level of cleanliness.