Antique furniture with wood veneers usually have a three layer surface. The solid wood is followed by an underlayment of wooden strips, the grain at right angles to the solid wood, and then the wood veneer is on top, usually adhered with hide glues. Some of the issues that occur with water exposure is that the wood strips, the veneer, and the solid wood of the furniture all absorb water and swell, but at different rates. The veneer is usually the first visible damage as it swells and buckles. But to properly repair and restore a piece of damaged furniture, the underlying layers must also be repaired. If cracks and splits in the wood are left, the structure that supports the veneer is unstable, and failure of the piece is likely.
Table tops are particularly difficult to repair correctly, and specialised equipment and supplies are often necessary. Because exposure to humidity, water, heat, and sun can damage wood in different ways, the veneer is usually taken off completely and the underlayment and solid wood studied for needed repair. Old hide glues are removed with solvents and surfaces sanded and checked for cracking. On a vertical piece of wood, such as a leg, a small crack can be easily filled in with wood putty, allowed to cure, and then sanded level. But this approach doesn’t always work on horizontal surfaces such as table tops. Aged wood is rarely level, and trying to fill in cracks, and then sand a surface level will cause the veneer, when it is added, to accentuate the uneven surface.
Specialist materials are used, and mechanical presses, to ensure that a repaired table top is perfectly level before the veneer is replaced. For old furniture, a two ply veneer, with wood grains going at right angles to each other, provides a more stable surface that will not show minute imperfections in the old wooden substrate as clearly. These thicker veneers use a special adhesive and usually require a mechanical press to adhere properly.
Replacing a water damaged veneer table top is an opportunity to provide proper wood conservation to a piece of furniture, and ensure its structural integrity and beauty into the future.