TSLAC Conservation frequently works on 19th-century federal and state volumes bound in sheepskin leather. These volumes often develop similar condition issues: detached or damaged spine coverings and detached boards. Aged sheepskin leather is uniquely prone to discolor when exposed to adhesives, even those that might normally be safe for use with other types of leather.
Conservators typically try to limit intervention as possible, but for these volumes, a fuller intervention offers many advantages. Here, a fuller intervention involves removing and stabilizing the spine covering and boards, and rebuilding the underlying structure with archival paper and tissue. This procedure solves a variety of common condition problems and allows losses to be discreetly filled beneath the leather with toned tissue. Leather discoloration issues are minimized because adhesive need not be applied over the top of most of the leather.
Smaller repairs actually present a larger challenge. For example, damage at the head or tail of the spine covering doesn’t warrant a fuller intervention, but it does pose many risks for leather discoloration. TSLAC Conservation has in recent years used a 40-gram weight toned tissue pre-prepared in-house with Lascaux adhesive and applied with heat in order to work over the top of the sensitive sheepskin leather. Heat application minimizes the leather discoloration that would likely appear with brush application, even though Lascaux is typically safer for leather. The need for this level of caution demonstrates just how delicate sheepskin leather can become over time.