Fake craquelure on paintings

While examining an Italian 15th century panel painting in our
collection, we have observed a very fine, accurately executed fake
craquelure pattern which is only observable under magnification. The
fake craquelure is located in an area of green drapery in the
background which has been over-cleaned in the past. In 1934
curatorial sources commented on the darkness of the painting and the
difficulty of making an attribution. In 1935 another art historian
commented on the much improved appearance (after treatment) and a
definite attribution was made. The painting was acquired by a
collector who later donated it to Glasgow Museums. We do not have
any records of the treatments carried out but the original
craquelure, which is clearly visible in other areas, is very feint
in the green background. The original paint is very thin and dotted
with the remains of a brownish glaze. The fake craquelure has been
added to this area as described below. We are not questioning the
authenticity of the painting but are intrigued as to how such an
effective craquelure pattern, which is not visible to the naked eye
but only under magnification, was achieved.

Appearance of fake craquelure under microscope:

    Uniform black colour
    Applied 2-dimensionally i.e. no incising
    Runs across original cracks
    Runs across small losses and obvious retouching

Quality of fake craquelure:

    Not visible to the naked eye and therefore assumed to be
    intended to deceive

    Minute detail, very similar shape, size and pattern to original
    cracks

    Occasionally prominent original cracks have been accentuated

Technical observations:

    No pigment particles are visible (possible ink medium?)

    Splatters have been accidentally produced when running across
    cracks, old fillings or uneven areas.

    Black smears are present on the borderline of flesh tones where
    the original crack is well preserved and artificial ones are
    unnecessary, This could have happened

    when cleaning off overlap. The same smear effect can be observed
    on the top edges of craquelure.

    Lies between varnish layers. Mechanical removal of the top layer
    does not remove craquelure pattern.

    Use of solvents does remove craquelure pattern, together with
    old varnish/over-paint.

Possibilities

    1. Painted on under microscope

        This would probably take months to do and require a one hair
        brush

        It would be difficult to achieve this degree of regularity
        over a surface as big as this (ca. 30cm2)

    2. The use of some sort of stencil or applied resist layer

        These would not enable painted lines to exactly follow the
        original cracks, as is sometimes the case, although those
        could have been added later by hand.

        These techniques are unlikely to produce the sort of
        splatters observed

Has anyone come across a similar false craquelure pattern or is able
to suggest a plausible technique to produce one. We would be most
grateful for any suggestions or comments.

Sylvia Krauss
Paintings Conservator
Glasgow Museums Resource Centre
200 Woodhead Road, Glasgow G53 7NN
Office +44 141 276 9470
Studio +44 141 276 9415


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                  Conservation DistList Instance 24:18
               Distributed: Thursday, September 30, 2010
                       Message Id: cdl-24-18-020
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