Re: Tortoiseshell

["Shayne Rivers" <s.rivers@vam.ac.uk>]

Greg,
A common problem, I'm afraid.
This is the bit of Conservation of Furniture (Rivers and Umney, pub.
Butterworth Heinemann, out late May 2003) that may be helpful:

Hawksbill turtle was the major source of the turtleshell found on
historic furniture. Although both the hawksbill and green turtle are
protected species, farmed green turtle can provide a legitimate source
of shell when this is required for replacing losses, without endangering
the survival of turtles in the wild. The Cayman Island embassy may be
contacted for details of such turtle farms and shell. Hawksbill shell is
very thermoplastic and could be heat welded or moulded around compound
shapes. The shell of the green turtle is less thermoplastic and less
transparent. Freshly killed turtleshell was prepared for use by
immersion in hot water. The shell may be cramped flat or shaped after
sufficient immersion and will maintain a given shape after it has
cooled. It may be thicknessed and surface faults removed by planing,
scraping and sanding. 

Many alternatives to turtleshell and horn have been utilised and include
a variety of pigmented fill materials from sealing wax, shellac, epoxy
resin, polyester resin, guitar picks and acetate sheets (Lochhead, V,
(1989) 'Tortoise-shell substitute veneer' in Conservation News 38, pp.
31-32 ). It may be possible to cast replacements, though polyesters may
require the addition of an inert powder to impart opacity. Imitation
turtle shell can be made from epoxy resin tinted with Orasol dyes (Ciba
Geigy). As with the ivory substitute described above, the dyed epoxy can
be accurately rolled to thickness between guides or in a rolling mill
before it has completely set (Fig. 15.1a&b). If a thermoset is cast
directly into the surface a reversible isolating layer should be used.

Hope this helps,
Shayne Rivers
Senior Furniture Conservator
Victoria and Albert Museum
South Kensington
London SW7 2RL