Butyl rubber-coated polyester fabric with various concentrations of MT carbon black in the rubber was examined for peel strength. The peel strength was tested after aging at 90 degrees C for different time intervals and after exposure to gamma radiation of various ionizing radiation doses. The air permeability and the dielectric properties of the proofed fabric were also measured. The optimum concentration of MT carbon black was found to be 20 phr and the optimum radiation dose was 2500 Gy/h.