Titanium white

I have recently started PhD research at the Rijksmuseum Amsterdam,
the Cultural Heritage Agency of the Netherlands and Delft University
of Technology.  The PhD project concerns the possible risks of
deterioration of titanium dioxide white paints in 20th century art
or conservation work.  Titanium dioxide reached the market around
1920 and it is a known photo-catalyst.  This means that titanium
dioxide, exposed to UV-light and in proximity of atmospheric oxygen
and water, can form radicals which can attack the surrounding
organic material (e.g. binder).  These chain reactions may cause a
changes on the paint surface.  To counter these effects titanium
white pigments nowadays are coated and mostly made of the less
photo-catalytic crystal structure rutile.  In the development
towards stable pigments it can be assumed that photo-catalytic
pigments have been on the market and have been used by artists and
in conservation work forming a risk for the artworks.  With this
project I intent to investigate these risks and get a better
understanding of the underlying processes.

In this first stage of my project I am looking for examples of
paintings where a negative effect of titanium white has been
observed, paintings where the use of titanium white is known or any
suggestion for possible case study material.  Any example or
suggestion would be greatly appreciated.  Thank you in advance.


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                  Conservation DistList Instance 28:4
                   Distributed: Tuesday, July 1, 2014
                        Message Id: cdl-28-4-017
                                  ***