Silicon carbide is harder and sharper than aluminum oxide at equivalent grit sizes, which means it cuts cleaner with less pressure — important on clear coat where too much pressure causes heat and burn-through. It also fractures more consistently at fine grits, producing a uniform scratch pattern that polishes out predictably. Above grit 600 on any painted surface, SiC is the right grain. For earlier stages of sanding on wood or primer, see the aluminum oxide collection.

Same grain, same grit range (2000–5000), same foam construction — different coverage area. The 6" disc covers large flat panels efficiently — hood, roof, door skins. The 3" disc gets into tighter areas — around mirrors, door jambs, bumper curves — where a 6" disc would rock off the surface. Most body shops keep both sizes on hand.

Yes, but wet is better above grit 2000 on clear coat. Dry use at 2000–3000 works on lacquer and wood finishes where heat is less of a concern. On automotive clear coat, I always add a mist of water or sanding lubricant — it keeps the disc cutting cleanly, prevents micro-scratches from heat, and extends disc life noticeably. The foam backing holds up to wet use without delaminating.

The SpotFix discs use PSA (peel-and-stick) attachment and require a 1-1/4" foam backing pad — typically a soft foam spot repair pad used in SMART repair kits. The PSA bond is firm enough for machine use at low speed but releases cleanly when you're done. Do not use these on a standard hook-and-loop backing pad — the PSA won't adhere to the velcro surface.

For heavy orange peel: start with BN38 1000–1500 wet sheet to level the texture, then step to FlexPro 6" at 2000 → 3000 → 5000 to refine the scratch. For light orange peel or texture only: start directly at 2000 with the FlexPro 6" foam disc. After 5000, compound and polish. Skipping grits at this stage leaves scratches that compound can't remove — don't jump from 1500 straight to 5000.

Yes. The BN38 sheets work dry on wood finishes — particularly useful between lacquer or varnish coats at 320–600 grit to knock down nibs and dust without cutting through the finish. At coarser grits (80–180), they're effective for shaping and stock removal on hardwood. Wet use on wood is less common but works for final finishing on oiled or waterborne finishes.

A single dust nib typically takes 3 discs — one each at 2000, 3000, and 5000 grit. A panel with 5–10 nibs uses 15–30 discs. At $0.28 per disc from a 100-pack, a full panel's worth of spot repair costs under $9 in abrasive. The 100-pack format is sized for professional use — enough for a full day of SMART repair work without restocking.

Only on fully cured clear coat — not fresh. Fresh clear coat (under 24–48 hours depending on product and temperature) is too soft for any abrasive, including a scuff pad. Once cured, the FV19 scuff pad is safe for adhesion prep before applying additional coats or protective film. Its non-woven structure won't leave deep scratches that show through the next coat.

The FV19 non-woven matrix cuts at roughly the equivalent of 320–600 grit sandpaper, depending on pressure and surface hardness. Because the abrasive is embedded in a three-dimensional fiber structure rather than bonded to a flat backing, it produces a finer, more random scratch pattern than sandpaper at the same nominal grit — which is why it's preferred for adhesion prep where you want scuffing without visible scratches.

Yes. FastPlus Abrasives USA ships all orders from a US warehouse. Most orders arrive within 3–5 business days. FlexPro foam discs, SpotFix spot repair discs, BN38 wet & dry sheets, and FV19 scuff pads are all stocked and ready to ship. Visit fastplus.us for current inventory.

Two signals: the disc stops cutting (you're making passes but the surface texture isn't changing) and the foam backing starts to compress unevenly or show tears at the edges. Unlike paper-backed discs, foam discs don't glaze — they just gradually lose abrasive density. When you notice you're applying more pressure to get the same result, the disc is past its useful life. On clear coat, a worn disc is worse than no disc — it generates heat without cutting, which can soften and distort the surface.

Think of it as the final stage of a three-collection workflow. Start with ceramic grain for aggressive stock removal and primer work (grits 40–400). Move to aluminum oxide for general finishing and between-coat prep (grits 80–800). Finish with silicon carbide foam discs and wet sandpaper for clear coat leveling, orange peel removal, and final polish prep (grits 800–5000). Each collection hands off to the next — this one closes the loop.