FEMA correspondence regarding historic building cleaning treatments, March 2002

NYC 9/11 Public Portal Document

' MAP, 15. 2002 1 1 :26AM O. 792 P. 29

A cleaning system appropriate for a specific masonry material may not be appropriate for adjacent masonry mortar joints.. The removal of pa on mortar joints should be avoided if possible.

Reducing the strength of the removal agent 'and/or the pressure applied for removing t~ e paintlsta n can minimize "clean spots" left q;x masonry.

Masonry surfaces should be tested with non-staining ph strips after removals are cgmpleted iri order to ensure that the substrate has been adequately neutralized. Neutralizing a surface involves removing all cl'remical and/or cleaning agents from the been neutralized can lead to subsequent damage of the fabric. .A substrate that has not historic fabric. Applied Paint (Sign age) to Significant Interior Historic Fabric: If paint (si~ ag}e is applied to significant interior fabric (e.g. murals, mosaics, PP • decorative metals) an experienced architectural and/or art conservator should be consulted regarding any possible to successfully remove applied overpaint from treatment or removal. It is even the most decorative or fragile substrates.

'Health, Safety, and Environmental Issues:

Tt is the responsibility of the Applicant to obtain ill 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 Manua!for 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 referenced in these performance standards, are available on the Internet; keyword Preservation Briefs.

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NYC-WTC 000094071