Frequently asked questions

Foam and rubber blocks compress under pressure, which hides imperfections like orange peel, ripples, and low spots. As Ryan Evans of Count's Kustoms puts it: "Most blocks out there will absolutely lie to you — they'll tell you it's straight but it's really not."

Linear blocks use a rigid polycarbonate base that's harder than the surface you're sanding. Because the base doesn't flex where you don't want it to, it maps out every high and low spot with 100% accuracy. The result: truly flat panels with no hidden surprises after paint.

The Vertebrae design is the spine of every Linear block. The base is CNC-machined polycarbonate with precision-cut rings that control how much the block flexes. All edges are routed and radiused — no sharp corners that could gouge your work.

The rings serve two purposes: they let the block conform to curved panels (like fenders and quarter panels) while maintaining even pressure distribution across the entire sanding surface. Wherever you place your hands, the pressure transfers evenly to the base — no hot spots, no uneven cuts.

Rigid: Zero flex. Best for perfectly flat surfaces — hoods, roofs, deck lids — and for the initial rough cut on body filler while it's still slightly soft.

Flex (Semi-Flex): Moderate flex — roughly half the bend of an Ultra Flex. The sweet spot for most bodywork. Follows gentle curves while still maintaining a true sanding surface. The 18" flex is the most commonly used block on just about any car.

Ultra Flex: Maximum flex. Designed for compound curves, rolled fenders, and dramatic body lines. The longer the block, the more it can flex — a 32" Ultra Flex can wrap around a Volkswagen fender. Use these for the initial cut on heavily curved panels, then work in a cross-X pattern to blend.

8": Detail work, tight areas, accent lines, and small spot repairs.

12": Moderate curves, transitions between panels, and working into body lines.

18": The workhorse. Probably the most commonly used block on any car. Great for doors, fenders, quarter panels, and picking spots after the initial block-down.

24": The minimum length to get serious flex for curved panels. Panel-to-panel work on hoods and large surfaces.

32": Large panels with significant curvature. This is what shops use on those dramatic rolled fenders.

As a general rule: use longer blocks for your initial cuts across large areas, then step down to shorter blocks to finesse transitions and details.

When you fold sandpaper and wrap it around a block, the folds create cushion — and that cushion lies to you, just like a foam block does. It hides orange peel and cellulite that you'll only discover after paint.

Linear's continuous sticky-back sandpaper adheres directly to the flat polycarbonate surface. As true as the block surface is, that's how true the sandpaper will be. No folds, no cushion, no surprises. Available in dry grits for bodywork and wet grits (800–2000) for color sanding.

The ceramic abrasive stays sharp significantly longer than conventional paper — comparable to 3M Cubitron, but in a sticky-back format designed for hard blocks.

Absolutely. Linear blocks are used by high-end shops for wet sanding clear coat before buffing. The polycarbonate base is waterproof and won't absorb water or develop mold.

Pair them with Linear's sticky-back wet sandpaper (800–2000 grit) for color sanding. The rigid, true surface eliminates finger grooving and ensures you're cutting the clear flat — not just chasing the texture of the orange peel.

Ryan Evans at Count's Kustoms has been wet sanding with Linear blocks for over a year: "The advantages we've had using the Linear blocks have been night and day."

Hyper Flex blocks have a hard polycarbonate side and a foam side in one block. They're designed for dramatic curves and rolls — like front filler panels, bumper transitions, and areas where even an Ultra Flex can't follow the contour. Flip to the foam side when you need a softer touch on delicate curves.

Mini Detail sets are compact, dual-sided blocks for precision work: removing nibs and runs in clear coat, sanding hard-to-reach areas, working accent lines and body details. Refinish Media called them "a game changer" and "one of my favorite if not the favorite block out there for detailing."

L-Series (L-411, L-417, L-418) is Linear's high-build DTM (Direct to Metal) epoxy primer. It's a true 4:1 epoxy — not a hybrid — designed to be used from bare metal up through final block sanding. One product from metal up.

Key specs:

• 65% solids by volume / 76% by weight — very high build with minimal shrinkage
• 48-hour cure — slow by design so all solvents escape before the primer skins over. Fast primers trap solvent and shrink later, revealing scratches after paint.
• Sands to a fine powder without plugging paper — unlike vinyl-heavy epoxies that gum up immediately
• Acts as a built-in guide coat — the color difference and sheen make lows and highs visible without separate guide coat application

Available in Blue (L-411), Grey (L-417), and Black (L-418). Kits include activator, or buy the activator separately.

Rinse with water and wipe down after each use. The polycarbonate won't absorb water or develop mold. For sticky residue from sandpaper adhesive, use a little adhesive remover or rubbing alcohol.

Proper cleaning extends the life of your blocks and ensures the sanding surface stays true. Watch our cleaning tutorial on YouTube for a quick walkthrough.

Yes — and that's a good thing. The biggest adjustment: use light pressure. Three fingers, let the block do the work. Don't knuckle down like you would with old foam blocks.

Because the polycarbonate base is rigid and true, it cuts efficiently with minimal effort. Ryan Evans says: "You're actually doing it twice as fast but not putting in nearly the effort. It makes the job easier, faster, and a thousand times better."

Work in a cross-X pattern on curved panels. Use longer blocks for initial cuts to establish flatness, then step down to shorter blocks for detail work and spot corrections.

Linear blocks are used by DIY enthusiasts and high-end professional shops alike:

• Count's Kustoms (Las Vegas) — Ryan Evans and crew have been using Linear blocks for over a year
• The Spray Source — authorized retailer and advocate, featured in multiple tutorial videos
• Refinish Media — independent comparison of 8 block brands over 8 months: "It's hard to beat a Linear block"
• Professional restoration and collision shops across the US and Canada
• DIY painters getting professional-grade results at home

All products are made in the USA in Antigo, Wisconsin, and backed by a Limited Lifetime Warranty.

All Linear Blocking Tools are backed by a Limited Lifetime Warranty. Coverage includes product failures caused by normal use and normal operating conditions. Damage caused by misuse, abuse, accidents, unauthorized modification, improper storage, or cosmetic wear is not covered.

Please review our Warranty Policy for full coverage details and claim instructions.

If your order included Order Protection and you need to file a shipping issue claim, start here: Order Protection Claims Form.

Claims for lost, damaged, or stolen shipments are handled by Order Protection, not Linear Blocking Tools.