Prussian blue

I am a student working on an african mask from Gabon (ethnous group
Fang, 19th century) and I have analysed the polychromic surface of
the face. FTIR analysis identified the red underlaying surface (a
kind of preparation layer under the surface pigments) as a
composition of ochre with traces of Prussian blue.

In the literature, Prussian blue is mentioned to have appeared
synthetically in 17th century but it has been found occasionally on
archaeological iron objects.

Has anyone heard of Prussian blue used in association with ochre in
african artefacts? Or of ochre iron oxides turning into Prussian
blue under certain conditions? Could this happen naturally or could
it be intentional?

Maya Froidevaux
Haute Ecole d'Arts Appliques Arc
2300 La Chaux-de-Fonds
Switzerland


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                  Conservation DistList Instance 19:37
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                       Message Id: cdl-19-37-015
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