Side
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The side (or outer rim) is a critical component in the cabinet construction of both grand and upright pianos. In most manufacturing processes, the side is attached after the installation of essential internal elements, including the action, soundboard, and strings. However, certain high-end instruments—such as Steinway grand pianos—feature a simultaneous construction of the side and the structural frame, enhancing overall rigidity and resonance.
Removable Elements and Structural Variations
In grand pianos, various parts of the side assembly are designed to be removable for maintenance and access. These include the rear cover, the front cover (often hinged together), the cylinder (or keyboard cover), and the fallboard. In upright pianos, the front portion of the cabinet is typically enclosed with a combination of panels, incorporating both the cylinder and the fallboard. The top lid generally opens from front to back, although some models may feature a side-opening lid, particularly on the left-hand side.
The back panel (or backboard) of upright pianos may be screwed rather than glued into place. When this is the case, it can be removed relatively easily during maintenance or inspection.
Materials and Structural Composition
The panels used in piano cabinetry can be constructed from solid wood, plywood, or particleboard, each offering distinct structural and acoustic properties. Solid wood panels are typically veneered on both faces to minimize the risk of warping over time. Plywood offers a more stable structure with resistance to deformation, while particleboard—though heavier due to its high glue content—is commonly used for lids in grand pianos due to its mass and density.
Despite its advantages, particleboard presents one critical drawback: its susceptibility to screw hole damage. Over time, the holes can become stripped, especially in high-torque or load-bearing areas. To mitigate this issue, manufacturers often reinforce screw connections with solid wood inserts.
Surface Treatment and Protective Finishes
The side coverings and cabinet panels not only serve aesthetic purposes but also protect the underlying wood from environmental influences such as humidity and temperature changes. After careful sanding, the wood surface is typically treated with filler and sealant, followed by stains and multiple coats of finish to achieve a protective and visually pleasing layer.
In American-built pianos, the most common finishing material is lacquer, which offers a satin appearance often enhanced with steel wool treatments. In contrast, European and Asian pianos predominantly use polyester finishes, known for their high-gloss sheen. Both materials have distinct advantages and disadvantages: lacquer is easier to apply and repair but offers less resistance to scratches and vapor penetration; polyester, on the other hand, provides a tougher, more water-resistant seal but is more brittle and vulnerable to cracking due to temperature-induced expansion or contraction of the wood.
