Discs
Pro
Grit · 80-400 assorted
Mirka Gold 5-inch Hook & Loop Disc Assortment
Clicks in smooth. Finnish-made. Doesn't ask you to stop.
Grit profile
400 grit sandpaper
Extra Fine
Wet sanding clear coat. Plastic finishing.
What 400 grit is for
400-grit is where wet sanding starts to dominate. It’s standard for color-coat prep on auto-body, between-coat sanding on clear finishes, and the first refinement step on metal heading toward polish.
Projects at 400 grit
- · Wet sanding auto color coat before clear
- · Between-coat sanding on instrument lacquer
- · First metal-finishing pass after coarse shaping
- · Smoothing fiberglass and composite repairs
- · Pre-polish on stainless steel
Abrasive materials
- · silicon carbide (default for wet sanding)
- · aluminum oxide (dry)
- · ceramic
Common mistake
On clear coat, 400 is too aggressive for finish wet sanding — drop to 1000+ once the orange peel is leveled.
Top pick at 400
Mirka Gold 5-inch Hook & Loop Disc Assortment
Clicks in smooth. Finnish-made. Doesn't ask you to stop.
Catalog fit
6
Current SKU matches in this grit lane.
Common forms
2
Forms represented here, led by discs.
Head to head
2
Comparison pages currently touching this stage of the sanding climb.
Use this grit when
The surface still needs this stage.
- · Wet sanding clear coat. Plastic finishing.
- · This is refinement territory. It improves the surface that is already close rather than rescuing a rough one.
- · On this site, 400 grit shows up most around auto-body, fine furniture, 6-inch orbital sanders, and auto paint prep.
Skip this grit when
The job is earlier or later than this.
- · Skip this grit if the surface still has deep scratches, filler ridges, or obvious machine marks from coarse paper.
- · Skip it unless the abrasive itself is labeled for wet use when you plan to add water.
Recommended at this grit.
Discs
Pro
Grit · 50-3000 set
Diamond Hand Polishing Pad Set (50-3000 grit)
For the hard surfaces that don't open up for just anything.
Sheets
Mid
Grit · 400
3M Wetordry — 400 Grit
400 wet. Where primer stops being primer and starts being a base.
Discs
Pro
Grit · 80-400 assorted
Festool Granat 5-Inch Disc Set — Multi-Grit (25-pack)
The disc the Festool deserves. Everything else is settling.
Discs
Pro
Grit · 120-400 assorted
Mirka Trizact 5-Inch Disc Set — Multi-Grit (25-pack)
Finnish precision. Pyramid grain. The finishing stack.
Discs
Pro
Grit · 80-400 assorted
Festool Granat 6-Inch Disc Set (25-pack)
Six-inch format. Festool quality. Everything the name promises.
Head to head
Comparisons in this lane.
Mirka Gold 5-inch Hook & Loop Disc Assortment vs. Diablo 5-inch ROS Discs — 120 Grit (50-pack)
Finnish precision or American volume.
Read the breakdown →
Mirka Gold 5-inch Hook & Loop Disc Assortment vs. 5-Inch Random Orbital Sander + Disc Starter Bundle
You either have the sander or you don't.
Read the breakdown →
Questions people ask
The practical part.
What is 400 grit actually for?
400 grit is for wet sanding clear coat. plastic finishing. This is refinement territory. It improves the surface that is already close rather than rescuing a rough one.
What should come before and after 400 grit?
The safe lane is usually 320 -> 400 -> 600. You can stretch that a little on easy material, but large jumps usually leave scratches behind.
Which forms make the most sense at 400 grit?
On UltraRough, this grit shows up most in discs and sheets. That reflects where shoppers usually need this cut level in the real world.
Keep moving
Follow the climb.
320 grit The step before 400 grit. 600 grit The next step after 400 grit. Discs See discs that commonly show up in this lane. Sheets See sheets that commonly show up in this lane. Use the grit selector Start from the project instead of the number. Read the full grit chart See the entire progression from coarse to mirror.