Sofa

Solid wood members and plywood panels can form the sofa’s load-bearing skeleton. Plywood distributes wood grain directions across bonded veneers, while solid members provide attachment points and shaped rails. Joints, fasteners and panel geometry determine whether the frame stays aligned; naming the timber alone does not establish its durability.

Steel springs can support seat cushions and return toward their original geometry when a person stands up. Some sofas use pocketed coils, others zigzag springs or webbing. The steel stores elastic energy, but the attachment system and spacing control how that support is distributed across the seat.

Flexible polyurethane foam creates a compressible cushion with a network of polymer cells. Its formulation and structure influence firmness, recovery and fatigue. Foam density and perceived softness are different measures, so a heavier cushion is not automatically firmer or more comfortable for every person.

A polyester fibre layer can wrap the foam, soften transitions at its edges and help the cushion fill the cover evenly. Loose or bonded fibres behave differently from a continuous foam block. They may flatten or shift over time even when the underlying frame remains serviceable.

A woven polyester cover provides the visible, repeatedly touched surface. Yarn construction and weave affect texture, snagging and abrasion as well as the polymer itself. Removable covers can make cleaning or replacement easier, but a fabric that resembles wool or linen is not necessarily made from those fibres.