Film-backed sanding discs are the standard in production body shops for a reason: the film substrate maintains consistent thickness and flatness across the face of the disc even as it flexes over curved panel surfaces, which means the abrasive cuts evenly without the high spots and low spots that paper-backed discs can develop as they conform unevenly to contoured surfaces. At 320 grit, these discs sit in the range where the real prep work happens — after filler has been shaped with coarser grits and before you move into the finish-preparation work of 400-600 grit wet sanding before paint or primer.
6″ Film Frip Sanding Discs — 320 Grit, 50/Box from Polishing Systems Inc provides the professional 320-grit sanding disc in the right quantity for shop use. Fifty discs per box at the film-backing specification used by production body shops that need consistent, repeatable sanding results across dozens of repair panels per week.
What These Discs Are
6-inch hook-and-loop (Velcro) sanding discs with a film (polyester or mylar) backing layer instead of the paper backing used in consumer-grade sanding discs. The “Frip” designation refers to a specific film grip product series. 320 grit is a medium-coarse abrasive grade — below the coarser grits used for initial shaping (80-180 grit) and above the finish-preparation grits (400-600 grit) used before color application. Designed for use on random orbital sanders, DA sanders, and other 6-inch hook-and-loop sanding tools.
Key Features and Why They Matter
- Film backing — polyester film provides consistent substrate thickness and greater tear resistance than paper backing. So what? The disc maintains its geometry as it flexes over contoured surfaces, delivering more even abrasion without the hot-spot cutting that paper discs can develop.
- 320 grit — the practical working grit for body filler leveling (after 80-180 shaping), primer sanding, and coarse surface prep before moving to finer grits for finish preparation.
- 6-inch diameter, hook-and-loop — the standard attachment system for professional random orbital and DA sanders. Compatible with any 6-inch hook-and-loop sanding backing pad.
- 50 discs per box — professional quantity. Individual disc cost at 50-count box pricing is appropriate for production shop use where disc consumption is measured in dozens per week.
- Consistent cut across the disc — uniform film backing and abrasive coating produce consistent sanding action from the center to the edge of the disc.
What These Discs Are NOT For
Not for final finish sanding before color coat — 320 grit leaves visible scratch marks that require subsequent sanding with finer grits (400-800-1200+) before a quality finish can be achieved. Not for use on glass without extremely light pressure and wet sanding technique. Not for wood, ceramics, or non-automotive surfaces. Do not use dry on surfaces that require wet sanding for optimal finish quality and heat control.
Who Uses These Discs
Auto body shops doing production repair work requiring body filler sanding and primer surface preparation. Paint prep technicians leveling primer before color application. Detail shops doing surface prep before paint correction compound application on heavily scratched vehicles. Fleet maintenance body shops doing patch repairs. For finish-preparation grits, see the P800 Film Grip Disc and P1200 Film Grip Disc for progressive grit sequences.
How to Use
- Attach the disc to a 6-inch hook-and-loop backing pad — press firmly to ensure full hook-and-loop engagement across the disc face.
- Set your sander to appropriate speed for 320-grit work — moderate speed is sufficient; excessive RPM at this grit level generates heat and can load the disc with melted filler material.
- Work in overlapping circular or cross-hatch passes across the surface.
- Inspect frequently — 320 grit removes material quickly on body filler and soft primer. Check your level often to avoid oversanding.
- Change the disc when it loads with residue or loses cutting efficiency — a loaded disc works harder than a fresh disc for less result.
- Progress to finer grits for finish preparation before moving to paint or primer topcoat.
Frequently Asked Questions
What grit do I progress to after 320?
After 320 grit on body filler and initial primer, the typical progression for automotive body work moves to 400 grit for the scratch refinement step, then 600-800 grit for finish preparation before primer sealer or guide coat, and 1200+ grit for final wet sanding before color application. The exact grit sequence depends on the paint system and the quality of finish required.
Can these discs be used wet?
Film-backed sanding discs are generally compatible with wet sanding — the film substrate does not absorb water like paper backing. For wet use, the hook-and-loop backing on a 6-inch disc may experience reduced adhesion when saturated. Test on your specific machine/backing pad combination before committing to wet use on production work.
How many discs does a typical body shop use per week at 320 grit?
Consumption varies significantly by workflow and the number of repair panels being processed. A single-bay shop doing 3-5 repairs per day might use 5-15 discs per day at 320 grit, depending on repair size and filler work volume. At that rate, a 50-disc box lasts roughly 1-2 weeks — making the 50-count box a reasonable monthly or bi-monthly reorder quantity for a moderate-volume shop.
Why film backing instead of paper backing?
Film backing (polyester or mylar) does not absorb moisture the way paper does, maintains more consistent thickness under use, and provides better tear resistance than paper on a power sander. For production body shop use where disc consumption is high and consistency matters, film-backed discs produce more reliable results than paper-backed alternatives at equivalent grit.
