Nylon is the standard envelope fabric used in most modern hot-air balloons.
Balloon envelopes need to be lightweight, strong and able to withstand repeated inflation and deflation. Ripstop nylon meets those requirements well, so it became the usual material for modern sport and passenger balloons. The fabric is commonly coated to improve its resistance to heat and air leakage.
The envelope is not the same as the basket or the burner. The basket is often made from woven materials such as wicker with a supporting frame, while the burner heats air entering the envelope. The lower portion of the envelope also receives special protection because it is closest to the flame.
Early experimental balloons used paper, silk and other materials. Modern nylon should therefore not be projected backward onto the Montgolfier balloons, whose construction differed substantially from today’s designs.