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Subject: Sticky film on sepia diazotypes

Sticky film on sepia diazotypes

From: Miguel Josi Laiginha Lourenco <miguelaiginha<-at->
Date: Monday, April 27, 2009
Karen Potje <kpotje [at] cca__qc__ca> writes

>At the CCA we have discovered a large group (hundreds) of sepia
>diazotypes, each of which has a small (4 x 6 inches) rectangle of
>transfer film applied to the verso which bears the title of the
>project and other project information. This film is degrading,
>oozing and sticky.  As a result, the plans stick together, and
>sticky residue is being transferred to the rectos of adjacent
>documents. ...

    Vilela, Marta; Ferreira, Luisa, M. and Vieira, Joao.
    Discolouration of Architectural Photoreproductions.
    Causes and Prevention, Restaurator. Volume 27, Issue 1, Pages
    1-8, ISSN (Print) 0034-5806, DOI: 10.1515/REST.2006.1, 23 March

    Abstract: When applied to architectural drawings, the term
    photoreproduction means a copy from the original drawing that
    was produced using a process similar to the photographic
    process. In architectural archives, these prints, especially
    diazotype prints, are conservation staff's main preservation
    concern. Diazotype reproductions usually show a reddish pink to
    orange discolouration. When an interleaving sheet of paper
    separates diazotype prints, discolouration is gradually
    transferred onto this paper. Furthermore, discolouration goes
    through the interleaving paper and reaches the next document.
    The results of this study show that this phenomenon is caused by
    the coupling agent used in the diazo process. Under alkaline
    oxidative conditions, this agent suffers polymerisation
    reactions leading to discolouration.

    You could check it here


Miguel Lourenco

                  Conservation DistList Instance 22:64
                   Distributed: Tuesday, May 5, 2009
                       Message Id: cdl-22-64-004
Received on Monday, 27 April, 2009

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