By Ann Kennedy Haag, Chief Conservator of Frames, Furniture, Objects and Gilding;
and Michael Young, Associate Conservator of Furniture
(Above) Art Deco desk before treatment
Loose, lifting and buckling veneer are common problems encountered with historic furnishings. Historic furnishings are constructed from various species of wood and are adhered almost exclusively with the natural adhesive animal hide glue. Various factors contribute to the delaminating and distortion of veneers. An ideal environment rarely experiences rapid and/or dramatic fluctuations in temperature or humidity. Housed in optimal environmental conditions, an animal adhesive will maintain its integrity for many years; however, such conditions are seldom the case.
Recently, The Chicago Conservation Center was asked to assess and treat a historic Art Deco desk. The desk is entirely covered with different species of veneer; the case under the veneer is also a differing secondary wood. As one may guess, various woods will react differently to changes in temperature and humidity; thick and hard woods react slowly, thin and soft woods rapidly. Swell and contraction may create opposing forces, especially if woods have been adhered with the grain direction in opposition. Additionally, the natural animal glue reacts to environmental change. The Art Deco desk had experienced environmental fluctuations resulting in many areas of loose and lifting veneer. The problem has been recurrent, as old repairs were evident.
(Above) Example of wood grain expansion directions
As can be seen in both the pre-treatment and post-treatment photos the veneer had been applied to create a decorative pattern. In order to create such a pattern, it is necessary to adhere the grain lines in opposing directions. Consequentially, the results of expansion and contraction caused the glue to fail as it was stressed beyond its capacity to adjust. The desk exhibited classic problems associated with shrinkage. As may be seen in the treatment photo of the stacked door panel, portions of cross grain veneer were lost and replaced.
Case edges which are veneered are vulnerable to damage. As the base wood shrinks, the veneer is left protruding beyond the case and may easily be caught on dust cloths, clothing and carpet. Veneer lost from this desk was replaced with like species; the photographs show the repairs before color was applied for ease of differentiation. Had the original detached veneers been saved they would have been reapplied. Loss compensations were colored locally in order to retain the historic finish.
(Above) Large section of veneer that had pulled away from the wood.
(Above) Example of damage caused by carpet and flooring.
As a steward of historic furnishings, one should always be cognizant of the environment in which a collection is maintained. Preservation is a matter of not only keeping your collection clean and protected but also of controlling the interior environment. An understanding of materials, and sensitivity to their inherent weaknesses, will assist with their long-term care and preservation. This type of education ensures our collective cultural heritage will be maintained for many generations.
(Above) Art Deco desk after treatment