Historic Preservation - Technical Procedures
Removing Bitumen From Limestone
National Capitol Region Specifications
Removing Bitumen From Limestone
REMOVING BITUMEN FROM LIMESTONE
A. This procedure includes guidance on cleaning and removing
localized bitumen residue from limestone surfaces. For
guidance on the general cleaning of surface dirt on
limestone, see 04460-03-R.
B. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. 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).
1.02 QUALITY ASSURANCE
1. Contractor performing the work shall have a minimum
of 5 years experience in masonry restoration work
of the type described for this project.
2. If requested by the Owner, furnish a statement of
the experience and qualifications of the firm and
of the key personnel who will work on this project.
Include the names and addresses of successful
projects completed, and for each, the name and
address of the owner and the architect.
B. Reference Standards:
1. Secretary of the Interior's "Standards for
2. Preservation Brief No. 1, "The Cleaning and
Waterproofing of Historic Masonry Buildings".
C. Test Panels: Each alternative method for each type of
A. Hydrochemical Techniques, Inc.
P.O. Box 2078
Hartford, CT 06145
B. ProSoCo, Inc.
755 Minnesota Avenue
P.O. Box 1578
Kansas City, KS 66117
800/255-4255 or 913/281-2700
C. KRC Research Corp.
A. Alkaline cleaners and water rinse, such as "HT907"
(Hydrochemical Techniques, Inc.), "Sure-Klean Limestone
Pre-Wash/After-wash" (ProSoCo, Inc.), "Ion 417 fluoro-
surfactant" (KRC Research Corp.), or approved equal.
B. Bitumen removal: Following scraping to remove bulk,
apply solvent containing petroleum distillate (in
poultice, if required) equal to Sure-Klean Asphalt and
C. White absorbent material (molding plaster, untreated
white flour, white tissue, paper towels, powdered chalk,
talc, fullers earth or laundry whiting).
D. Mineral water
E. Plastic sheeting
F. Clean dry towels for blotting the area after treatment
G. Masking tape
H. Clean, potable water
A. Pressure water rinsing equipment (measuring between 100
and 400 psi for low-pressure; between 400 and 800 psi for
B. Fan-type spray tips (15 degree fan spray)
C. Soft fiber-bristle brushes
D. Stiff natural fiber-bristle brush (Tampico)
E. Glass or ceramic container for mixing the solution
F. Wooden utensil for stirring the ingredients
G. Wooden spatula
3.01 ERECTION, INSTALLATION, APPLICATION
A. General rinsing of unsoiled stone:
1. All limestone surfaces shall be water rinsed in
order to blend in areas that are chemically cleaned
to remove stains with unsoiled areas of stone.
2. Water rinse: Maximum 600 PSI, 5-10 GPM, 15 fan
angle, not less than 6" from stone surface, at an
angle of 45 to 90 from wall surface, hot water
B. Cleaning of soiled limestone with alkaline cleaner:
1. Pre-wet area to be cleaned.
2. Apply alkaline cleaner with soft fiber brush or
spray. Allow to stand on surface approximately one
hour. Agitate with a stiff natural fiber bristle
3. Pressure rinse surfaces. Repeat rinsing until all
traces of chemical have been removed.
4. Apply acid neutralizer. Repeat pressure rinse.
5. Repeat the process as required.
C. Bitumen Removal:
1. Protect adjacent stone with polyethylene sheeting.
2. Scrape off bulk of bitumen using a wooden spatula,
taking care not to damage the stone surface.
3 Dissolve remainder with specified solvent. Swab
4. If required to dissolve deep stains, apply solvent
in poultice and keep wet for 4-8 hours by sealing
in plastic sheeting. For guidance on preparing and
applying poultices, see 04455-02-R.
END OF SECTION