The invention aims to solve the problem of prior art EL devices that undesirable defects form in dielectric layers, and especially the problems of EL devices having dielectric layers of lead-base dielectric material including a lowering, variation and change with time of the luminance of light emission, and thereby provide an EL device ensuring high display quality without increasing the cost. In the method, a recirculation loop containing polyols along with an effective amount of water, and a recirculation loop containing isocyanates, are each partially evacuated. The top component includes barrier material suitable for preventing pests from biting humans or animals resting on the bedding. The feedback element processes the voltage into an output current.