A DA sander follows the surface contour and can miss low spots. A rigid sanding block spans across high and low spots and cuts the highs down evenly, which is how you flatten a panel. For guide coat reading, primer leveling, and straightening repaired panels, hand block sanding is the correct technique. DA sanding is faster for material removal; block sanding is more accurate for flatness.

Match the strip to your block. The 7.8 inch strip fits the FB1 short block and any standard 2.75 inch wide short sanding block - best for edges, door jambs, spot repairs, and areas where the longboard cannot reach. The 16.5 inch strip fits the FB2 longboard block - best for panel leveling, guide coat reading, and primer sanding on large flat surfaces like hoods, roofs, and doors. Both strips use the same PuroFilm ceramic abrasive and grit range P60-P400.

Match the roll to your block backing. Velcro roll for hook-and-loop (Velcro) sanding blocks - the FastPlus FB1 and FB2 both use hook-and-loop faces. PSA roll for smooth PSA-backed blocks like Durablock or 3M Stikit blocks. The ceramic abrasive is the same on both rolls. PSA changes faster in production; Velcro repositions without losing grip. If you are unsure which block you have, check whether the block face is fuzzy (hook-and-loop) or smooth rubber (PSA).

No. The FT77 strips and both rolls are for dry sanding only. The hook-and-loop and PSA backings are not rated for wet use. For wet hand sanding, use the BN38 SiC wet/dry sheets (9x11 inch, waterproof) cut to fit your block. The BN38 sheets are available in P80-P2000 and hold up to water without delaminating.

Apply guide coat (dry powder or spray) over the primer, then block sand with P180-P220 to reveal high and low spots. High spots will sand through the guide coat quickly; low spots will retain guide coat. Continue sanding until the guide coat is uniformly removed across the panel. Finish with P320 before base coat. Use the FB2 longboard with 16.5 inch FT77 strips or the Velcro roll for this process on large panels.

The FB2 longboard block has an adjustable flex mechanism that allows the block face to bow slightly convex or concave. Use the flat/convex setting for flat panels like hoods, roofs, and doors where you want maximum contact across the full block length. Use the concave setting for curved surfaces like fenders, bumpers, and quarter panels where a flat block would only contact the edges and skip the center. Adjust before attaching the strip - do not flex the block with a strip attached as it can cause the strip to detach at the edges.

The roll is more economical per linear foot of abrasive. A 13-yard roll gives you approximately 39 feet of abrasive that you cut to any length with no waste. Pre-cut strips (25-pack) cost more per foot but save time in production — no cutting, consistent length every time, and easier to grab and go during a job. For shops that do high-volume block sanding, the roll pays for itself quickly. For occasional use or when strip consistency matters, the pre-cut 25-pack is the more convenient choice.