Matter art

I am working on a badly cracking and delaminating Tapies 'Matter'
painting from 1958. The typical materials used during this period
are often sand and marble dust, mixed with an alkyd varnish
(Titanlux), applied directly to a commercially prepared canvas, and
painted with latex paint. The thickness of the paint layer varies in
our case from 1/4 inch thick to paper thin.  Severe cracking and
interlayer cleavage quickly developed after the creation of the
work. Buckling caused by the weight of the paint layer was
temporarily stabilized by the artist who glued a thin fabric on the
back of the canvas, over the horizontal cross-bar. As with many of
the artist's paintings from that era, the paint layer is curling
away from the tacking edges and delaminating as much as 1/2 inch
away from the support. Some of the cleavage has created pockets that
reach 20 inches in diameter. Here is a brief overview of the
composition of the paint matrix to give you a better idea of what is
at hand:

    Canvas estimated to be linen

    Sizing (estimated to be rabbit skin glue)

    Two ground layers (analysis shows oil related binder, barium
    sulfate and driers)

    Blue "imprimatura" layer (analysis shows polyvinyl propionate
    and Prussian blue)

    Paint layer (estimated sand, marble dust, oil-modified alkyd and
    latex)

(I can send photomicrographs of a cross-section of the paint matrix
as well as a photo of the delaminating edge if you want a visual
reference)

My questions to you are:

The delaminating always occurs at the interface of the paint layer
and the blue "imprimatura" layer. While polyvinyl propionate is
known for its inherent elasticity, the pigment volume concentration
of the sand and marble dust paint layer is very high, and both might
be fairly incompatible. These factors, combined with gravity and
shrinkage of the paint layer during drying, is probably to blame for
the delaminating. Has anyone consolidated this type of matrix and if
so, how were the pockets of blind cleavage addressed?

Has anyone successfully managed to reduce the planar deformations on
this type of painting?

The canvas is obviously insufficient in providing a strong and
stable support for the thick, heavy and rigid paint layer. Has
anyone dealt with reinforcing this type of work (lining, inserts,
etc.)?

Any suggestions or comments will be greatly appreciated.

Chantal Bernicky
Carnegie Museum of Art
412-622-3237


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                  Conservation DistList Instance 22:5
                  Distributed: Thursday, July 17, 2008
                        Message Id: cdl-22-5-014
                                  ***