How long should sandpaper last before it loads up ? I'm sanding the first thin sealer coat of shellac on baltic birch plywood. I'm only getting about four square feet before the disk "corns" to the point of useless. I'm using Klingspor's new green stearated discs, 220 grit. I've turned down the speed on my random orbital Bosh as far as it goes. I pre sanded the plywood sheet to 180 grit then sprayed Sealcoat, diluted 50%. Any suggestions on how to get better results? At this rate I could eat up 16 discs per sheet of plywood.