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

IDENTIFICATION OF IVORY BOOK COVERS
Ancient carvers managed to hand cut ivory into
a thin veneer cylinder, which was cut into pieces
and subsequently softened and mounted upon the
curved faces and hands of sculptures [1]. Medieval
book covers may have been made this way as there
are some early surviving ivory book covers as large
as 30 cm square [1].
The size of leaves was limited by the diameter of
tusks, until technology developed for the production
of larger sheets of ivory in the early 19 th century
[16]. Ivory was spiral cut with a reciprocating
saw into a scroll, steamed until soft, then subjected
to hydraulic pressure to flatten to a desired size
[16]. The resulting ivory had an increased flexibility,
a finer polish, and less grain patterns [17], but the
surface was often wavy and needed to be laid down
on stiff card before painting could begin [16].
Miniaturists were traditionally concerned about
the permanence and stability of their ivory leaves
[16]. Veneer cut ivory proved undesirable as the
ivory was prone to shattering into thin, parallel
segments [16]. Therefore, miniaturists continued
to cut leaves in the traditional manner, just as they
continued to use the same materials and techniques
since the 18 th century [16]. Since watercolour paint
did not readily adhere to the ivory material, miniature
leaves required the extra steps of degreasing,
whitening, and scraping [18].
Risks for Deterioration of Ivory
The most common instances of ivory deterioration
are warping, cracking and complications arising
from added materials. Ivory is a relatively stable
material, but only in a constant environment [19].
It is an anisotropic material, and is therefore susceptive
to warping and cracking on exposure to
heat or moisture [3]. Thin artifacts such as miniatures
and book covers are especially vulnerable,
as even moisture and heat from hands may be
damaging [3].
Warping
The risk of warping is increased when the ivory is
mounted on stiff backing cards, restricting natural
Figure 9. Severe warp of a portrait miniature at LAC.
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