The key to achieve professional results is to blend the areas receiving different preparation techniques, so that you achieve a more uniform finish. Picture framing is the difference in color and texture that becomes visible when finish is applied to a prepared hardwood floor. The best way to prevent picture framing is to screen the entire floor using 120 grit mesh screen, prior to applying any finish. Screening between coats of finish will also improve color and luster consistency. Sandpaper not removing old finish - If your floor has been painted, has a heavy finish or has is coated with mastic, you might experience loading .
Loading is simply clogging of the grit, resulting in loss of cutting capability.
This is a problem that the professional floor sander also encounters. If the sand paper no longer seems to be removing the old finish, check to see if the paper is clogged with old finish. If the paper is clogged, replace the paper. If you continue to experience problems, consider using coarser grit. Remember, you should use the finest grit possible to get the job done.