I've purchased a few of the Rotex sanding pads. I am a hobby woodworker so don't regularly use my rotex. I keep the sanding pads in the house because the one I got with the tool delaminated after a few years. The temperature in the house is about 80-85 degrees Fahrenheit throughout the year at its warmest. A new sanding pad never used delaminated and was probably a couple of years old. Is this normal where the white spongy material deteriorates that quickly? I wish the materials were more durable as these are expensive sanding pads. I assume these pad don't have a warranty.