The polyester fiber loses its ability to absorb after a couple of days and washing the core does not seem to help and good luck trying to get the water to dryout after you wash it. Try getting a roll of polyester batting at any fabric store or Walmart. It looks, feels, and wicks just like the original and, at least some of use here think it is the exact same think. I just cut it to fit and at 7 dollars for a 5 foot roll --that makes about a years worth of cores.