The Story Behind This Sofa
Arm design is where comfort is decided, and there are really only three families. A straight panel arm is the cheapest to build and the least comfortable - it gives you a hard vertical edge at exactly elbow height. A scroll arm that turns outward looks elegant but sheds your arm off the outside of the curve. A rolled arm, as here, turns the top inward and downward in a wide radius, so there is a broad padded surface for an elbow at rest and a comfortable place to lie against when someone stretches out along the sofa.
Building one is considerably harder. The roll has to be shaped over a curved frame member and stuffed to hold its section under a hand rather than collapsing, then upholstered on a compound curve where the fabric has to be eased in without a single pucker. Adding button tufting along that roll, as here, multiplies the difficulty - every button pulls on a curved surface and the grid must stay parallel to the roll all the way round.
The carved arm front is then fitted so the acanthus meets the upholstered roll cleanly with no visible transition.