Removing Soluble Salts From Limestone

CSI Division
Division 4- Masonry
Section
Limestone
Last Modified

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Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.

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We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.

PART 1–GENERAL

1.01 SUMMARY

  1. This procedure includes guidance on removing soluble salts from limestone.
  2. 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).
  3. For general information on the characteristics, uses and problems associated with limestone, see 04460-01-S.

PART 2–PRODUCTS

2.01 MATERIALS

  1. Distilled water
  2. Paper pulp made by boiling good quality blotting paper with distilled water and beating it until completely disintegrated and cellulose fibers mat together to form a pulp

2.02 EQUIPMENT

  1. Stiff bristle brushes (non-metallic)
  2. Vacuum

PART 3–EXECUTION

3.01 ERECTION, INSTALLATION, APPLICATION

  1. Clean stone of all debris, dust, oil, salt crystals, etc. by brushing with a stiff fiber bristle brush or by vacuuming.
  2. Thoroughly wet stone with clean, clear water just prior to applying poultice.
  3. Apply wet paper pulp (soaked in distilled water) to the stone completely covering and concealing all voids and surfaces.
  4. Keep pulp in position for three weeks or until completely dried and removed easily.
  5. After carefully removing the dried pulp, brush or vacuum to remove all salt crystals formed on stone surfaces.
  6. Apply fresh pulp as described in Section B through D above.
  7. Brush or vacuum to remove all salt crystals formed on stone surfaces.
  8. If high concentrations of soluble salts remain in the stone, repeat applications of poultice.

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Last updated: Aug 13, 2017
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