If the hole closes after the object is removed, you are working with a quality fabric. The backs of most chairs are 36 inches high, and the seats are usually 18 inches off the floor. Between the back and seat, what counts is the construction of the chair frame. Chair frames come in steel or wood, or a combination of both. Chairs with strong frames can be stacked without sustaining structural damage.
Wood frames are strong, but they're heavier than steel.
The strength of a steel-frame chair varies. Seats and backs . The seats and backs of Bertolini chairs are made of marine birch plywood. This type of plywood holds up especially well in Hawaii or the coastal Southeast, where humidity is a problem. North American Seating uses polymer resin boards that last longer than plywood.