While “sandpaper” is the generic term for abrasive sheets, it obviously does not describe all the various types of sanding supplies available! Sanding sheets may be paper, cloth, plastic film, fiber (similar to fiberglass) and now even mesh as in Mirka’s Abranet products.
The thickness (or “weight”) of the paper backing is rated in a scale A through F, with A grade being the lightest. Cloth backing is rated J, X, Y, T and M with J the lightest.
When choosing an abrasive sheet, these rating help you figure out what backing will best suit your needs. For sanding flat surfaces, a stiffer backing will help prevent digging in, or rounding over the edges, while a lightweight backer should be chosen to wrap around a profile sanding block to smooth moldings.
While it is important to choose the right sheet for the job, if you find yourself with the wrong backer for the task at hand, here are two tips:
1) Lightweight sheets can be bonded to a heavier backer to improve it’s performance and durability sanding flat surfaces.
2) Heavier backers can be “broken down” and made more flexible by rolling and unrolling the sheet into a tight tube shape. The many fine creases created will make it more flexible.
