Before placing the strong canvas on the seat, we need to identify the straight edge of the canvas. The canvas in fact must be laid with the sense of the length aligned with the front-back axis of the chair.
At this point cut the canvas leaving a 10 cm excess on each side. Place it on the springs and nail it with the 9 mm seed along the groove, folding the canvas towards the inside of the structure.
Carefully fix the canvas in correspondence of the legs and the different levels by folding it.
After nailing sew the canvas to the springs using a Greek path. This will make it more stable.