June 12, 2012
Sanding with Consecutive Grades of Sandpaper
As a result, the surface will be left with an uneven scratch pattern, with deep scratches in among the fine ones. Because these deep scratches fill with fine sanding dust, they may be nearly invisible to you until you apply a finish. Then the finish will darken the torn end-grain fibers in the deeper scratches, making them stand out from the surrounding surface. This will ruin the smooth consistent appearance of the surface.
Article provided from "The Workshop Companion, Sanding and Planing, Techniques for Better Woodworking" by Nick Engler. Permission of use granted by Rodale.