Why are the foam densities different for the backrest and the seat?
This question is asked when looking at the specifications of the LCH3 chair and wondering about the differences because the foam numbers and names written for the backrest and the seat are different.
This is because the seat, which must support body weight evenly, is filled with firm high-density foam, while the backrest, which must softly wrap the back, is separately filled with flexible foam.
The LCH3 chair features different foam configurations depending on the contact area. The backrest is filled with 25kg soft foam, and the seat is filled with 35kg medium foam, respectively[1].
The number marked on the foam indicates the density per unit volume. The seat is an area where body weight is concentrated when sitting, so the high-density medium foam, which supports firmly without sagging easily, distributes the weight. On the other hand, because the backrest is an area where the body leans comfortably, it has a structure tailored to wrap the back without causing pressure points by incorporating relatively soft foam. It provides stable support for the hips and flexible acceptance for the back, maintaining a comfortable balance even when sitting for a long time.
The resilience test standards or service life of the filling material used in the LCH3 chair have not yet been confirmed.