Pick the wrong sanding grit and you’ll either spend three times as long fixing the surface or commit a defect that the next coat won’t hide. Pick the right one and the work disappears under your hands. This guide is the explanation we give over the phone to customers who are working out a new abrasive workflow โ distilled into one page, with the practical rules of thumb that actually matter.
We’ll cover the grit ladder (what each number does), how to plan a grit progression for the most common materials, and the mistakes that cost shops time and money. If you’d rather just talk it through, call us at 403-250-3399 โ we’ve helped hundreds of Western Canadian shops dial in their sanding workflows and we’ll do the same for yours.
What “grit” actually means
The grit number on a sanding disc tells you how many abrasive particles fit per square inch of the abrasive grain. Higher number = smaller particles = finer cut.
Think of it as a continuum:
- 40โ80 โ coarse, aggressive material removal. You’re shaping the workpiece.
- 100โ150 โ medium, transitional. Smoothing out the marks left by the coarse grits.
- 180โ240 โ fine, finish-prep. Producing the surface a coating will stick to.
- 320โ600 โ very fine, between-coat or color sanding. You’re not removing material, you’re conditioning the surface.
- 800โ1500 โ ultra-fine, polishing. Mostly used in auto-body clearcoat work.
Different industries use different sub-ranges. A finish carpenter spends 95% of their time between 120 and 220. An auto-body refinisher spends 95% of their time between 320 and 1500. A heavy fabricator might never use anything above 80.
The cardinal rule: don’t skip more than one grit step
If you go straight from 60 grit to 220 grit, the deep scratches the 60 left behind will still be visible โ the 220 doesn’t have enough cutting depth to remove them. They’ll telegraph through your finish, and you’ll be re-sanding the whole piece a week later when the customer notices.
The safe progression rule is one step at a time through the standard grit ladder:
40 → 60 → 80 → 100 → 120 → 150 → 180 → 220 → 320 → 400 → 600 → 800 → 1000 → 1200 → 1500
You don’t need to use every step. But you can’t skip more than one. Most professional progressions use every other grit on the ladder โ for example, 80 → 120 → 180 → 220 โ because each grit is roughly 1.5ร finer than the previous one, and that’s the sweet spot for efficient material removal.
Grit progressions for common materials
Solid wood (furniture, cabinets, instruments)
Bare wood, before any finish: 80 → 120 → 180 → 220
That’s it. Going higher than 220 on bare wood actually hurts โ it polishes the surface so smooth that stain won’t penetrate evenly, and you’ll get a blotchy finish.
Refinishing painted or weathered wood: 40 or 60 to remove the old material → 80 → 120 → 180 → 220.
Between coats of waterborne lacquer or varnish: 320 or 400 grit. Just a quick scuff to knock down dust nibs and give the next coat something to grab.
Metal โ fabrication and welding
Weld grinding and stock removal: 40 to 80 grit on a flap disc or sanding belt. Stay aggressive.
Pre-paint surface prep on steel: 80 → 120 → 180. You want the surface tooth for paint adhesion, not a polished surface.
Stainless steel satin finish: This is where it gets specialized. After your initial cleanup, you switch from coated abrasives to non-woven (Scotch-Brite-equivalent) wheels โ fine, then very fine. Trying to satin-finish stainless with regular sanding discs leaves a directional scratch pattern that looks unprofessional.
Aluminum: Be careful with 40โ60 grit on aluminum โ it loads quickly because aluminum is soft. Lubricate with a stick lubricant or step up to 80 grit and stay there longer.
Auto-body refinishing
Stripping to bare metal: 80 grit with a sanding belt or DA, working slowly so you don’t burn through.
Smoothing body filler / Bondo: 80 → 120 → 180 → 220 → 320.
Primer prep before color coat: 320 → 400 → 600. Final pass is 600 if you’re going to spray a basecoat. 400 if it’s a single-stage.
Color sanding clearcoat (after curing): 1000 → 1500 → 2000 (or polishing compound from 1500).
This is where the Festool ETS EC 150 with Sia Siaspeed 1500 in 49-hole pattern earns its keep โ the dust extraction prevents the rogue particle that ruins a panel.
Drywall finishing (commercial scale)
Single-pass on cured joint compound: 180 grit on a multi-hole 5″ disc.
For commercial volume work, that’s the entire workflow. You don’t need a progression โ joint compound is soft enough that a single 180-grit pass produces paint-ready surface.
Coated vs. non-woven abrasives
Beyond the grit number, you also choose between two abrasive families:
Coated abrasives (sanding discs, sanding belts, sandpaper sheets) โ the abrasive grain is bonded to a backing in a single layer. Cuts fast, removes material aggressively, leaves a directional scratch pattern that gets finer as the grit climbs.
Non-woven abrasives (Scotch-Brite-style pads, Siaair wheels) โ the abrasive is embedded in a 3D nylon mesh. Cuts slower, removes less material, leaves a uniform satin finish without directional scratches.
The simple rule: use coated for shaping and finish prep, non-woven for surface conditioning and final-finish polish on metal.
The four mistakes that cost shops time and money
1. Buying the cheapest disc. A $40 box of generic discs that load in 10 minutes costs more than a $70 box of Sia Siaspeed that cuts cleanly for an hour. Track cost-per-square-foot-sanded, not cost-per-box.
2. Wrong hole pattern. Festool 49-hole discs on a Mirka tool work fine. Multi-hole discs on a Festool tool don’t โ you’ll lose dust extraction and the disc clogs in 5 minutes. Match the pattern.
3. Skipping grit steps. Covered above. Always.
4. Sanding through the grit you’ll regret. Going to 320+ on bare wood. Going to 600+ on bare metal you’re going to weld. The next process step needs the right surface, not the smoothest possible surface.
Quick-reference grit selector
For the most common scenarios:
| If you’re… | Start with | End with | Skip these |
|---|---|---|---|
| Refinishing hardwood floors | 36 (drum) | 100 (orbital) | 60, 80 |
| Furniture pre-stain | 80 | 220 | 100, 150, 180 |
| Auto-body filler | 80 | 320 | โ |
| Stainless satin finish | 80 | Non-woven very-fine | use non-woven for last 2 steps |
| Drywall joints | 180 | 180 | single-step |
| Color-sanding clear | 1000 | 1500 | โ |
Stock the ladder you actually use
The cheapest way to keep a shop running is to have the four to six grits you actually use always in stock. We see shops chronically run out of one specific grit, and the production line idles while someone drives across town to a hardware store. The fix is a Business account with auto-reorder โ set up your standing order once, get a fresh case of your most-used grits delivered on the schedule you choose, and never run out again.
The most-stocked grits across our customer base are 80, 120, 180, 220, and 320. If those are your default ladder, we’ll keep them flowing.
Talk it through
If you’re spec’ing abrasives for a new line of work and you want a second opinion before you commit a thousand-dollar standing order to a grit progression that doesn’t fit, give us a call. We’ve worked through this conversation with hundreds of Alberta shops and we’ll get to the right answer faster than a forum thread.
Browse our full sanding catalog → Open a Business account → Custom belt sizes →
Published April 28, 2026 by IBEX Enterprises โ Calgary’s industrial abrasives supplier. Updated as our customers’ workflows evolve.