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Historic Preservation - Technical Procedures

Spectitle:

Cleaning Interior Limestone Walls

Procedure code:

0446005R

Source:

Hsr - Departmental Auditorium Bldg/Wash, Dc - Grier, Brown..

Division:

Masonry

Section:

Limestone

Last Modified:

02/24/2012

Details:

Cleaning Interior Limestone Walls



CLEANING INTERIOR LIMESTONE WALLS


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 surface dirt from
         interior limestone walls.  GENERALLY, THIS WORK SHOULD BE
         PERFORMED 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.   NOVA Chemical Company
         1520 Erie North
         Kansas City, MO  64116
         816/221-2712

    B.   ProSoCo, Inc.
         755 Minnesota Avenue
         P.O. Box 1578
         Kansas City, KS  66117
         800/255-4255 or 913/281-2700

2.02 MATERIALS

    A.   Limestone Cleaner:  Mildly acidic cleaner diluted with
         two parts water and containing 5 parts per million (ppm)
         of hydrochloric acid, 1 mg/m3 oxalic acid, 25 ppm glycol
         ether, and 10 mg/m3 ethylene glycol such as "Interior
         Stone Cleaner" (ProSoCo, Inc.), or approved equal.

    B.   Varnish and Paint Remover:  Solvent based methylene
         chloride stripper specifically formulated for removing
         paint and adhesives from masonry such as "Graffiti
         Remover" (NOVA Chemical Company), "Sure Klean Graffiti
         Remover" (ProSoCo, Inc.), or approved equal.

    C.   Clean, potable water (heated to a temperature effective
         and tested for cleaning procedure and approved by RHPO).

    D.   Clean, soft cloths

2.03 EQUIPMENT

    A.   Pressure water rinsing equipment (measuring between 100
         and 400 psi for low-pressure; between 400 and 800 psi for
         medium pressure).

    B.   Fan-type spray tips (15 degree fan spray)

    C.   Polyethylene bucket

    D.   Soft, fiber bristle brushes

    E.   Sponges


PART 3---EXECUTION

3.01 EXAMINATION

    A.   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 and contain flow of run-off in compliance
              with municipal codes so as not to damage
              surrounding materials.  Comply with municipal codes
              regarding containment and disposal of cleaning
              materials.

    B.   Surface Preparation:  

         1.   Before proceeding with cleaning operations, remove
              all miscellaneous hardware from the surface to
              prevent any discoloration.

         2.   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.

    A.   Dilute limestone cleaner with water (in accordance with
         results of test cleaning) and mix solution in a
         polyethylene bucket.

    B.   Pre-wet limestone surface using a low pressure warm water
         wash (between 100-400 psi).

    C.   Apply limestone cleaner to limestone using a soft, fiber
         bristle brush.  Allow to stand for 3-5 minutes or as
         determined by testing.

    D.   Apply more cleaner while lightly brushing stained areas
         with a soft, fiber bristle brush.  Continue to scrub the
         surface for length of time as determined by testing.

    E.   Thoroughly rinse the surface using a low pressure warm
         water wash.  

         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.

    F.   Use sponges and clean, soft cloths to remove excess water
         from the surface of the limestone; allow the surface to
         dry.

    G.   To remove paint or adhesives that may remain on the
         surface, apply a varnish or paint remover following
         manufacturers instructions.

                         END OF SECTION