Don't use the pads much, only the sheet. I have a few sets for many years now, guess every set has seen hundreds of pens. They are washed in the washing machine by my wife, she tosses them in a one of these mesh bags for fine undies. After they come out of the washer she hangs them up and lets them dry. For this duty she gets a pen from time to time:wink:. It seems to me, the older these MM sheets get now, I can do less pens with them before a cleaning is needed. But then I rotate three or four sets.