Details: |
General Cleaning Of Exterior Limestone
GENERAL CLEANING OF EXTERIOR LIMESTONE
THE CLEANING OR REMOVAL OF STAINS FROM STONE MAY INVOLVE THE USE
OF LIQUIDS, DETERGENTS OR SOLVENTS WHICH MAY RUN OFF ON ADJACENT
MATERIAL, DISCOLOR THE STONE OR DRIVE THE STAINS DEEPER INTO POROUS
STONES. USE THE PRODUCTS AND TECHNIQUES DESCRIBED HERE ONLY FOR
THE COMBINATIONS OF DIRT/STAIN AND STONE SPECIFIED.
PART 1---GENERAL
1.01 SUMMARY
A. This procedure includes guidance on the removal of
surface dirt and environmental pollution on exterior
limestone. GENERALLY, THIS WORK SHOULD BE ACCOMPLISHED
BY AN EXPERIENCED CONTRACTOR.
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
3. Submittals
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).
C. For precautions relating to pressure washing, see 04510-04-S.
PART 2---PRODUCTS
2.01 MANUFACTURERS
A. ProSoCo, Inc.
www.prosoco.com
2.02 MATERIALS
A. Limestone (unpolished): Sodium hydroxide, (pH 14), undiluted
such as "Sure Klean Limestone Prewash" and "Sure Klean
Limestone Afterwash" (ProSoCo, Inc.), or approved equal.
1. For heavy high pollution stains, an alkaline-based prewash such as "Sure Klean 766 Limestone & Masonry Prewash" or equal, follow manufacturer's instructions including rinse cycle.
2. Followed up with "Sure Klean Limestone & Masonry Afterwash, Restoration Cleaner, or Limestone Restorer" or equal, as per manufacture's instructions.
B. Clean, potable water (heated to a temperature effective
and tested for cleaning procedure and approved by RHPO).
2.03 EQUIPMENT
A. Pressure water rinsing equipment (measuring between 100
and 400 psi for low-pressure; between 400 and 1000 psi for
medium pressure).
B. Fan-type spray tips (15 -45 degree fan spray)
C. Stiff fiber-bristle brushes
D. Plastic spatula
PART 3---EXECUTION
3.01 EXAMINATION
A. Examine site conditions to determine that current
drainage is sufficient for adequately and safely removing
cleaning waste and run-off from the site.
B. Test clean a small, inconspicuous area to check for
adverse effects and damage to the material.
3.02 PREPARATION
A. Protection:
1. Protect surrounding materials on the site and
adjacent building surfaces from coming in contact
with the cleaning materials and run-off.
2. Provide workers with necessary protection against
cleaning chemicals, overspray and run-off.
3. Prevent cleaning chemicals from coming in contact
with any painted, polished or metallic surfaces.
4. Divert flow of run-off to drains in compliance with
municipal codes. Comply with municipal codes
regarding containment and disposal of cleaning
materials.
B. Surface Preparation:
1. Before proceeding with cleaning operations, remove
all miscellaneous hardware, anchors and bird
excrement from the surface to prevent any
discoloration.
NOTE: BIRD EXCREMENT IN CONTACT WITH CLEANING
SOLUTION WILL LEAVE A PERMANENT DARK-COLORED STAIN
ON THE SURFACE.
2. Check for open holes and joints in surface and
repoint mortar joints and caulk gaps around window & door openings, as required to prevent water and
cleaning solutions from penetrating deeply into the
wall.
3. Clean the limestone working from bottom to top.
3.03 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 TO DETERMINE EFFECTIVENESS OF
CLEANING METHODS, MATERIALS, EQUIPMENT AND WORKING PRESSURES
SELECTED BEFORE PROCEEDING WITH CLEANING OPERATIONS ON LARGER
AREAS. ADJUST METHODS, MATERIALS, EQUIPMENT, PRESSURES, ETC.
AS NECESSARY. DO NOT PROCEED UNTIL AN ACCEPTABLE CLEANING
OPERATION HAS BEEN APPROVED AND FULLY DOCUMENTED.
NOTE: DO NOT TREAT THE SURFACE WITH ACID CLEANER MORE THAN
ONCE.
A. Pre-wet limestone surface using a low pressure wash
(between 100 and 400 psi).
B. Apply a heavy coating of limestone pre-wash using a soft,
nylon bristle brush. Follow manufacturer's applications
instructions.
C. Allow to stand for one hour or as long as determined by
testing.
D. Thoroughly rinse the surface using high pressure water
(between 800 and 1000 psi). Rinse until no sudsing
remains.
1. Rinse all corners, moldings, and interstices to
remove all traces of chemical without damaging
surrounding materials.
2. Rinse water should be heated to 150-180 degrees Fahrenheit or
as determined most effective during testing.
E. While surface is still wet from rinsing off pre-wash,
apply limestone afterwash with a soft, fiber bristled
brush.
1. Dilute limestone afterwash with as much water as
determined effective during testing.
2. If surface has begun to dry, re-wet before applying
afterwash.
3. Cover all corners, moldings, and interstices of the
limestone.
F. Allow to stand for 3-5 minutes or as long as determined
by testing.
G. Thoroughly rinse the surface using high pressure water
(between 400 and 1000 psi), with a water flow of 6-8 gallons per minute.
1. Rinse all corners, moldings, and interstices to
remove all traces of chemical without damaging
surrounding materials.
2. Heat rinse water to a temperature determined most
effective during testing.
END OF SECTION
|
