Despite these qualities, the use of these adhesives in conservation
is discouraged. By their very nature as cross-linking polymers, they are
intractable and, therefore, not easily reversible.The most widely used adhesives at the Smithsonian Institution’s
Conservation Analytical Laboratory are hot and cold hide glues; there is
only minor use of synthetic resin emulsions or solvent-borne adhesives.
Cross-linking and multipart adhesives are almost never used as replace-
ment adhesives when joint failure is treated.
Knowledge of an object’s use and of the structural stresses that
will be placed on the object during that use is particularly important when
the choice of an adhesive treatment is made. A panel painting on a display
easel will experience different stresses from those of a painting that is
hanging, and the grain direction of a panel (and therefore its natural
potential for either strength or damage) could affect its exhibition or storage
orientation. In addition, the object may serve its function indefinitely in
controlled circumstances, but only briefly under adverse environmental
conditions. It is against this backdrop that an assessment of the object’s
condition must take place.Treating wood fractures
Because this article is especially pertinent to wood panels, extremely rare
cross-grain breaks will not be discussed. Instead, the focus will be on
breaks that are essentially along the grain, or longitudinal with respect to
the wood orientation of the panel.Simple fractures
Asimple fracture, whether partial or complete, requires only the introduc-
tion of an appropriate adhesive, alignment, and modest compression to
complete the reassembly. To speak of an “appropriate” adhesive, however,
is to be intentionallyambiguous, as there is a variety of possibilities.
Selection depends on such factors as the stresses the object must withstand
and the sensitivity of any decorative surfaces (no small consideration when
dealing with polychrome panels).
Apartial fracture ofan object that is still in one piece (sometimes
tenuously) does not always leave easy access to the gluing area. The glue
must be applied either by allowing it to flow into the void under gravity or
capillary action or by forcing it in under pressure by use of a hydraulic
device, such as a syringe.
Acomplete fracture presents immediately accessible gluing sur-
faces, and adhesive can be applied directly with a brush, spatula, or other
appropriate tool.
For both complete and partial simple fractures, the conclusion of
the gluing process is to align the parts to be unified and to apply only
enough restraint to hold them in place until the glue dries.Complex fractures
Complex fractures are particularly challenging when the gluing surfaces
are no longer adequate for the reassembly of the artifact, either because
the panel is distorted, leaving a void in the alignment, or because the glu-
ing surface itself is damaged by displacement or splintering of the woodSelection and Use of
Adhesives in Wood
Conservation
A S A W C 83