This may have been discussed before but here we go…There is a tool that the woodworkers use called an Abrasive Belt Cleaner,it is simply a giant eraser that you hold on the sanding pad while the tool is running,sandpaper will clog up before wearing out and this deal is well worth five bucks and will last a long time.You can get em at any woodworking supplier.I have one sheet of 320 that has polished at least five boards.As a footnote I use the gold colored 3M. sandpaper in the 180 thru 320 range way more betta than wet or dry.Keep on grinding.