Mexican feather mosaic

Ellen Pearlstein <epearlstein [at] hotmail__com> writes

>I am assisting a group of art historians who are interested in the
>technology and conservation of Mexican feather mosaics. These were
>part of a pre-columbian tradition for decoration that continued and
>was modified to produce Christian imagery in the colonial era. I
>would be interested in hearing about any technical studies or
>conservation treatment work that has been performed on these
>objects.

I am not familiar with the Mexican feather mosaics referred to and
no indication of their condition is given, but recent investigations
into laser cleaning and fading rates of Amazonian feathers might be
be of interest. Macaw feathers in various colours were assessed with
a detailed study of a red tail feather from a scarlet macaw. While
the macaw species in question would apparently not be found in
Mexico other types of macaw would be (eg the military macaw) and so
the results might be equally relevant to feathers on the Mexican
items.

Laser cleaning, using a Q-switched Nd:YAG laser at 0.9J/cm2 was
found to be more effective than vacuuming or swab cleaning and as
effective as cleaning in an ultrasonic bath, without apparent
disruption to the feather structure. The technique has most
potential in dealing with fragile composite feather objects which
can not be immersed (I imagine the feather mosaics would come into
this category), while avoiding the potentially disruptive
manipulation involved in more manual techniques.

The level of cleaning is largely determined by the fluence used--the
higher the fluence the more effective the clean, but the risk of
damage to the feather is also increased. In terms of fading the red
scarlet macaw feathers showed low light sensitivity using blue wool
data (Blue Wool standard 6, corresponding to ISO rating 6), though
using data for noticeable changes indicated an ISO light fastness
rating of 4. Needless to say, however, if the items are to be
displayed illumination strategies should err on the side of safety
until fading rates of all colouration in the feathers has been
adequately assessed.

Details of the studies are given in the following recent
publications:

    Solajic, M.R, M. Cooper, T. Seddon, J. Ruppel, J. Ostapkowicz
    and T. Parker.
    "Colourful feathers: multidisciplinary investigation of the
    Amazonian featherwork from the ethnographic collection at the
    National Museums and Galleries on Merseyside (NMGM) - initial
    results" in The Conservation of Fur, Feather and Skin, ed Margot
    M. Wright, Archetype Publications, London, 2002, pp69-78.

        This book also includes two other articles (Rae et al, and
        Schaeuffelhut et al) detailing the structure and
        deterioration of feathers and conservation of featherwork.

    Solajic, M.R, Boris Pretzel, M. Cooper, J.H. Townsend, T.
    Seddon, J.  Ruppel, J. Ostapkowicz and T. Parker.
    "A collaborative examination of the colourfastness of Amazonian
    featherwork: assessing the effects of exposure to light and
    laser radiation", in the ICOM CC 13th Triennial Meeting Rio de
    Janeiro Preprints, 2002.


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                  Conservation DistList Instance 16:33
                Distributed: Thursday, November 14, 2002
                       Message Id: cdl-16-33-009
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