Mayor's Office memo re: DEP meeting, Mar 2002

NYC 9/11 Public Portal Document

Friday 15 of Mar 2002, Mayor Office ->718 595 4544 Page 21 of 29

Cleaning Methods and Materials: The identification of type of soiling, dust, dirt, or debris and specific building materials (e.g. stone, cast stone, concrete, brick, terra cotta) is necessary in order to determine appropriate building cleaning programs.

Stone- Gentle water cleaning, and gentle water cleaning with a detergent, is appropriate. Mild acidic and alkaline chemical cleaning can be carefully considered for use based on material appropriateness if detergents are not effective. Air abrasive cleaning can be appropriate if abrasive ;wit types are carefully considered and tested.

Cast Stone- Gentle water cleaning and gentle water cleaning with a detergent is appropriate.

Brick- Gentle water cleaning, and gentle water cleanin , with a detergent, is appropriate. Acidic and alkaline chemical cleaning can be considered for cleaning unglazed brick when detergents are not effective. Acidic and strop; alkaline chemical cleaning solutions should not be used on glazed brick. Abrasive cleaning can potentially damage brick surfaces.

Terra Cotta- Terra cotta should not be abrasively cleaned, or cleaned with acidic or strong alkaline cleaning solutions as these methods can damage glazes. Water cleaning, or water cleaning in combination with a detergent, is appropriate.

Health, Safety, and Environmental Issues:

It is the responsibility of the Applicant to obtain all local, federal and state permits prior to the commencement of work and adhere to all local, state and federal laws with respect to the application and disposal of potential hazardous waste materials.

Sources: AIC Ethics and Standards Committee. "AIC Code of Ethics and Guidelines for Practice." Revised August, 1994.

Grimmer, Anne E. "Dangers of Abrasive Cleaning to Historic Buildings." Preservation Brief Number 6. Washington, DC: National Park Service, 1979.

New York Landmarks Conservancy. Historic Building Facades: The Manualfor Maintenance and Rehabilitation. New York: John Wiley & Sons, Inc., 1997.

Weaver, Martin E. "Removing Graffiti from Historic Masonry." Preservation Brief Number 38. Washington, DC: National Park Service, 1995.

Note: National Park Service Preservation Briefs, including those references in these performance standards, are available on the Internet; Keyword Preservation Briefs.

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