Historic Resources Committee

Renaissance Schallaburg Figures in a facade

Quick Links

Who we are

The mission of the Historic Resources Committee (HRC) is to identify, understand, and preserve architectural heritage, both nationally and internationally. HRC is engaged in promoting the role of the historic architect within the profession through the development of information and knowledge among members, allied professional organizations, and the public.

Expand all | Collapse all

NPS uses lasers to clean biofilm off the Jefferson Memorial

  • 1.  NPS uses lasers to clean biofilm off the Jefferson Memorial

    Posted 12-17-2019 14:18
    In the last HRC newsletter, @Christine Reynolds described how volunteers used a gel based cleaner on the Korean War Memorial. ​But on the other side of the Tidal Basin, NPS is also using lasers to maintain the dome of the Jefferson Memorial.

    Learn more about the process here >

    Have any of you used a similar method in your practice?

    Maggie Brown
    Washington DC
    20.09.24 John Parkinson AIAU course

  • 2.  RE: NPS uses lasers to clean biofilm off the Jefferson Memorial

    Posted 12-18-2019 19:34

    This is not a sustainable use of expensive lasers as they do cause abrasion to surfaces.


    The National Park Service, the GSA and other bodies have long used D2 biocidal cleaner and deterrent on historic buildings and monuments. But no sound scientific reasoning has been given for not continuing to use this approach.


    John F


    John A. Fidler DipArch, MAarch, MAconservation, AAGradDiplconservation

                               RIBA, IHBC, Intl Assoc AIA, FRICS, FSA, FIIC, FAPT


    John Fidler Preservation Technology Inc


    Marina Towers North

    4640 Admiralty Way, Suite 500

    Marina Del Rey

    California 90292-6636



    Tel: 310-496-5730

    Cell: 310-498-4973

    Email: johnfidler@jf-pt.com




    The message and attachments (if any) contained in this email are confidential, privileged and exempt from disclosure under applicable law, and are intended solely for the use of the addressee(s) hereof.  If you are not the intended recipient of this transmission, you are prohibited from disclosing, reproducing, distributing, disseminating or otherwise using its contents.  Delivery of this transmission to any person other than the intended recipient is not intended to waive any right or privilege.  If you have received this transmission in error, please promptly notify the sender by reply email and immediately delete the message.


    20.09.24 John Parkinson AIAU course