Discolored paintings

We have seen two batches of paintings from New Orleans that display
a  very odd discoloration (blackening) of certain passages of paint.

In one collection of portraits the blackening corresponded with
certain compositional elements, specifically the lighter tones of
the faces,  almost like a photographic negative.

In the second instance, a long, narrow oil on fabric that had been
(ineptly) rolled and in storage, the darkening occurred on broad
areas (not  related to compositional elements) where the structure
had collapsed on itself  with the weight of the water.  We suspect
that these parts of  the painting had stayed wetter and for a longer
period of time than the  rest of the image.  This is definitely a
paint condition, possibly a  chemical or physical change in the
pigmented layer, because it does not affect  adjacent bare canvas.

The discoloration appears to be through the structure,  not a
perceptibly three-dimensional deposit on the  surface.  Although we
know it's not the case, the paint looks as  though it had been
burned or seared, without the blistering.  Additionally,  there are
none of the other problems that normally come with water  damage
(cleavage, flaking, shrinkage)  associated with the darkening.

We would appreciate information or ideas anyone may have about this
unusual damage.

Cynthia Stow
Cumberland Art Conservation
3343 Acklen Avenue
Nashville TN 37212-3217
615-269-3868


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                  Conservation DistList Instance 19:23
                 Distributed: Friday, October 28, 2005
                       Message Id: cdl-19-23-021
                                  ***