General Cleaning Of Granite
- Procedure code:
- Hsr - Interior Building, Washington, Dc, 1988
- Last Modified:
- This procedure includes guidance on the removal of surface dirt and environmental pollution from exterior granite.
- 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 precautions relating to pressure washing, see 04510-04-S.
- Diedrich Technologies, Inc. www.diedrichtechnologies.com
- ProSoCo, Inc. www.prosoco.com
- Commercial masonry cleaner with a maximum 4% acid concentration, surfactants and wetting agents such as "Sure Klean Restoration Cleaner" - undiluted (ProSoCo, Inc.), or "Diedrich 101G Granite, Terracotta and Brick Cleaner" - diluted 1:4 to achieve a maximum 4% acid concentration (Diedrich Technologies, Inc.), or approved equal.
- Clean, potable water
- Pressure water rinsing equipment (measuring between 100 and 400 psi for low-pressure; between 400 and 800 psi for medium pressure).
- Fan-type spray tips (15 degree fan spray)
- Stiff bristle brushes (non-metallic)
- Plastic spatula
3.01 ERECTION, INSTALLATION, APPLICATION
NOTE: WHEN CLEANING, AVOID OVERCLEANING. AIM FOR ACHIEVING 85% CLEAN. MOST DAMAGE OCCURS WHEN ATTEMPTING TO CLEAN THE LAST 15%.
NOTE: TEST CLEAN A SMALL AREA BEFORE ATTEMPTING TO CLEAN LARGE AREAS.
NOTE: DO NOT TREAT THE SURFACE WITH ACID CLEANER MORE THAN ONCE.
- Saturate the granite with clean, warm water sprayed at a low pressure (between 100 and 400 psi). Remove bird excrement and debris from granite prior to the application of acidic granite cleaner (see 04510-02-R for guidance).
- Spray-apply cleaner evenly to the stained surface at 125 psi. or as recommended by manufacturer, or brush-apply cleaner using a soft fiber bristled brush.
- Allow cleaner to stand on the surface for 3-5 minutes or as recommended by manufacturer.
- Thoroughly rinse the surface with clean, clear water at medium pressure (between 400 and 800 psi). Nozzle should be held between 18 and 30 inches from the surface. Stone should be left clean without streaking or staining.