Series editors' preface - Wood Tools

(a) (b)
imitate the more costly turtle shell. Green horn
was boiled in nitric acid to give the yellow
colour of blonde tortoiseshell and after
neutralizing and washing was coloured using
a variety of materials as described by Wenham
(1964), Vuilleumier (1979) and Hardwick
(1981). The result is seldom subtle enough to
be very convincing, especially when compared
to the genuine article.
Further information on the history, tools and
techniques of working tortoiseshell and horn
can be found in Hardwick (1981), Jaeckel
(1978), Richie (1970, 1974), Vuilleumier (1979,
1980) and Wenham (1964).
Identification
Burek (1989) and O’Connor (1987a) suggest
investigation by transmitted light to differenti-
Other materials and structures 203
Figure 5.10 Plates from Diderot’s Encyclopédie ou Dictionnaire des Sciences, 1771 showing (a) the process of
flattening horn sections to form plates and (b) presses used for flattening horn plates
ate between horn and tortoiseshell. Bovine
horn exhibits a pattern of pigmentation that
follows the longitudinal axis of the fibre, while
tortoiseshell shows a mottled pattern (Figure
5.11). Marks in tortoiseshell go right through
the thickness but change slightly in size, shape
and position from one side to the other. They
are formed of aggregations of pigment particles
that under low power magnification in
transmitted light give a granular appearance
similar to photographic grain. Blonde tortoiseshell
from the plastron can be distinguished
from clear horn by lack of the striations or
corrugations present in horn.
Marks in horn stained to imitate tortoiseshell
are always on the surface, are not granular or
grainy, and often show evidence of brush
marks. Resin imitations of tortoiseshell may