The orbital motion of the
UDM can generate quite a bit of heat in the backing plate (the change of direction creates friction in the velcro, and heat from the machine itself can migrate into the backing plate). The combo of heat and heavy polishing seems to degrade the center of the pads.
My solution was an extra backing plate and multiple pads. I peel back the pad every few panels to see if it's starting to hold heat, and swap plates if necessary to allow one to cool. I've found it's only really a problem when you're doing heavy correction, and working at speed 6 for long stretches of time.
FWIW,
Tort