Fax forwarding DEP briefing materials for Mayor's meeting, March 2002

NYC 9/11 Public Portal Document , , ’A,,

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

Cleaning .Methods and .Mate ria l.s:>:fl"he identification of type oPsoiling. dust, dirt, or debris and specific building materiafs (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 xxith a detergent, is appropriate. .Mild acidic and alkaline chemical cleaning can be carefully considered for use based on • material appropriateness if detergents are not effectixe. .Air abrasive cleaning can be appropriate if abrasive grit 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 cleaning with a detergent, i.s appropriate. Acidic and alkaline chemical cleaning can be considered for cleaning unglazed brick when detergents C* are not effective. .Acidic and strongCP alkaline chemical cleaningz> solutions should not be used on glazed brick. .Abrasive cleaning can potentially damage brick surfaces.

Terra Cotta- Terra cotta should not be abrasix ely 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 Envii oninental 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 with re.spect to the application and disposal of potential hazardous waste materials.

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

Grimmer. Mine 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: Mcuiuai for A/aiiiteitance and Rehabilitation. New York: Jolin Wiley & Sons, Inc.. 1997.

Wea\ er. 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 reference.s in these performance standards, are available on the Internet; Kevword Preservation Briefs.

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