e-conservation the online Magazine 16, oct 2010.pdf

IDENTIFICATION OF IVORY BOOK COVERS
varnish applied over the ivory, distracting from the
natural beauty of the underlying ivory. Acetone
swab could be used to remove varnish, however it
is likely too risky to attempt removal of the varnish
as the ivory is inset into the metal frames
(Figure 13).
Warping
The removal of backings from portrait miniatures
often reduces the pressure that is causing them
to warp [24]. Miniatures are placed face down
and a thin scalpel blade is used to peel away the
backing, ensuring it is secure on a curved support.
Adhesives may require softening with a damp blotter
[23], less than 50% ethanol in water [20], or
10% Laponite solution through a tissue [23]. In
miniatures, the backing cards are an addition to
facilitate painting of the ivory. In books, the backings
are the book board, an integral part of the
structure and intention of the object. Thus despite
warping, it is not advisable to remove the
ivory from the card, nor reline the ivory.
The warping of ivory is a serious issue for portrait
miniatures as it affects the delicate paint layer and
may escalate until the ivory exceed the dimensions
of its case [22]. Ivory pieces can be placed in a
chamber conditioned with silica gel at 65-70%
RH for 10 minutes up to 2-5 hours, then clamped
between Plexiglas ® sheets [23]. This successfully
relaxes ivory to a more flattened state.
In addition, a Gore-Tex ® humidifying system has
been adapted from paper conservation to flatten
miniatures on ivory [24]. The miniature is placed
concave side down, between layers of Gore-Tex ® ,
silicon paper, blotting paper, and plastic [25]. Gore-
Tex ® allows a controlled amount of moisture to
pass through the ivory, and if necessary, increased
weighting will gradually flatten the ivory in 4-8
hours [26].
Though the silica gel and Gore-Tex ® methods do
reduce irregular distortions, it is often not possible
or wise to attempt to completely flatten the
miniature [24]. A safe alternative to attempting
to force the ivory flat is simply to accept some
distortion [24]. In fact, specialized sink mats can
be made with 2-ply rag board [23] or Plastazone,
which allow responses to changes in environment
from the portrait miniatures [24].
Though there is a significant warp in the ivory of
these books, flattening treatment is not recommended.
There are too many mixed materials in
the books to attempt flattening. Each of these
materials would respond differently to the moisture
introduced in flattening treatments. Furthermore,
Book 1 and Book 2 exhibit natural curving
which do not conform to the text block, nor should
it be forced. Book 3 shows restrained buckling
that is caused by various pressures exerted from
the metal framing, adhesive and varnish. If these
pieces were detached, they would benefit from a
relaxing treatment from either silica gel chamber
or a Gore-Tex® procedure.
Cracking
Ivory cracks and losses are the result of former
stresses and distortions, meaning pieces may not
align and will be difficult to successfully repair
[19]. Thus, they should be treated in the early
stages as soon as possible to avoid increased damage
[24]. Unfortunately, very extreme warping
and cracking of ivory is essentially irreversible [3].
Prior to treatment of ivory cracks, individual pieces
must be flattened first [20], with the backing paper
removed [24].
Experimentation to find the ideal adhesive for
treating ivory resulted in nearly every material
being used in the past [27]. Mowilith DMC2 is
currently recommended based on CCI test results,
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