Removing Efflorescence From Ceramic Tile
- Procedure code:
- Hspg Prepared For Nps - Sero
- Ceramic Tile
- Last Modified:
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 efflorescence from ceramic tile using a hydrochloric acid solution.
CAUTION: DO NOT USE THIS TREATMENT ON GLAZED TILE.
B. Efflorescence is a condition where white (salt) deposits form on the surface of the tile. The formation of salts is usually a sign of excessive amounts of moisture in the tile. Salt deposits on the tile surface may develop from:
- Soluble compounds within the tile or in the soil.
- In the presence of water, these compounds gradually migrate to the wall surface, where they remain when the water evaporates.
- These types of surface deposits are water soluble and can usually be removed by washing the surface with water from a garden hose supplemented by scrubbing with a stiff bristle brush.
- Improper or insufficient rinsing of tile after chemical cleaning or repointing.
- The penetration of rain into the tile through deteriorated mortar joints.
- Exposure to air pollution, which can result in the formation of thick sulfate (salt) crusts on the underside of moldings and eaves, areas not regularly washed by rainfall.
- Capillary movement of moisture through tile, the drying out of walls associated with a damp proofing treatment or the elimination of a ground water source may increase the amount of salt at or near the wall surface.
C. These deposits are generally not harmful to the building, just unattractive. However, they should be washed from the surface as soon as possible. Some salt deposits are water-soluble for only a brief period after reaching the atmosphere. Carbon dioxide in the atmosphere eventually converts these salts into water-insoluble carbonates, which are impossible to remove without the use of acids.
D. 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. Hydrochloric Acid (30-35%):
- A strong corrosive irritating acid.
- Other chemical or common names include Chlorhydric acid; Hydrogen chloride; Muriatic acid* (generally available in 18 degree and 20 degree Baume solutions); Marine acid*; Spirit of salt*; Spirit of sea salt*.
- Potential Hazards: TOXIC, CORROSIVE TO FLESH; CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS, FLAMMABLE.
- Available from chemical supply house, drugstore or pharmaceutical supply distributor, or hardware store.
B. Clean, potable water
C. Clean natural fiber rags
- Garden hose and pneumatic spray nozzle
- Stiff bristle brushes (non-metallic)
A. Before proceeding with steps to remove efflorescence, first decide the cause and extent of the problem and make repairs as required:
- Determine the age of the structure: Efflorescence on older buildings is typically caused by the presence of soluble salts in the construction combined with moisture.
- Determine the location of the efflorescence: Examination may show where the water is entering.
- Are the salt crystals accumulating on the joints or on the units?
- Can any changes in the wall composition or in the adjacent surroundings be recognized that might show the source of the problem?
- Examine the condition of the tile:
- CAREFULLY EXAMINE the wall for open gaps or cracks in joints and around openings that could allow water to enter the building.
- Are joints properly caulked or sealed?
- Are flashings and drips in good condition?
- Are there open or eroded mortar joints in copings or in sills?
- Carefully note the condition and profile of the mortar joints.
- Repair cracks in tile and/or repoint as necessary before proceeding with the cleaning operations.
- Examine wall sections and details of construction: Carefully examine roof and wall junctures and flashing details for possible sources of moisture entry.
- Examine laboratory test reports on the materials: The problem may stem from the composition or misuse of the material.
- Provide adequate wash solutions (i.e. water, soap and towels) before starting the job.
- Whenever acid is used, the surface should be thoroughly rinsed with water as soon as its action has been adequate. Otherwise it may continue etching the tile even though the stain is gone.
3.03 ERECTION, INSTALLATION, APPLICATION
NOTE: DO NOT TRY MORE THAN ONE TREATMENT ON A GIVEN AREA UNLESS THE CHEMICALS USED FROM PRIOR TREATMENT HAVE BEENWASHED AWAY.
CAUTION: DO NOT USE THIS TREATMENT ON GLAZED TILE.
- Mix 5% hydrochloric acid in water.
- Using stiff, natural bristle brushes, scrub the affected area with the acid solution.
- Thoroughly rinse the surface with clean, clear water and allow to dry.
- Repeat the process as necessary to achieve the desired level of cleanliness.