A solid sandpaper grit guide saves time, prevents rework, and makes paint and coatings lay down the way they should. Therefore, at Legacy Coatings, we see most “mystery finish problems” start in prep, not in the spray booth. That is to say, when the grit choice is off by even one step, scratches telegraph through primer, basecoat, or clear, and the surface never levels right.

What “grit” really means in real work

Grit is the size of the abrasive particles on the paper or disc. Consequently, lower numbers cut faster and leave deeper scratches, while higher numbers cut slower and refine the surface. However, the right number depends on what you are removing and what you are applying next.

The simple rule that keeps you out of trouble

Match the grit to the next product layer. For instance, if you are heading into primer, you need enough tooth for bonding, but not so much scratch that primer cannot fill it. In other words, every step should leave a scratch pattern that the next step can cover or refine.

The grit ranges and what they are best for

This section is the practical sandpaper grit guide most people wish they got on day one. Moreover, it is built around common refinish and coating workflows we see every week at Legacy Coatings.

40 to 80 grit: fast shaping, heavy removal

Use 40–80 when you must remove thick material, level filler, or knock down severe corrosion. Therefore, it is for shaping and stripping, not final prep. However, the scratch pattern is aggressive, so plan on stepping up through multiple grits afterward.

120 to 180 grit: leveling bodywork and initial feathering

Use 120–180 to refine filler, feather edges, and level primer surfacer build. Consequently, it is a common bridge zone that removes 80 grit scratches without clogging too quickly. That is to say, if you stop here, expect to keep refining before any basecoat work.

220 to 320 grit: prep for primer and many industrial coats

Use 220–320 when you need a controlled profile that still gives bite. Moreover, many primers and some industrial coatings like this range because it balances adhesion with manageability. If you are unsure, check the product sheet, or ask Legacy Coatings to match the grit to the system you are using.

400 to 600 grit: prep for basecoat and topcoat systems

Use 400–600 when the panel is straight and you are prepping for color. Therefore, this range reduces scratch mapping under bright lights and metallics. However, if your primer is not fully leveled, jumping straight to 600 can polish high spots while leaving low texture behind.

800 to 2000 grit: denibbing, blending, and finishing steps

Use 800–2000 for refining after paint, sanding dirt nibs, or blending edges. Consequently, this is where technique matters more than pressure. In addition, these grits often work best wet, with light passes and frequent inspection.

The step-up method that actually works

People often jump too far between grits and then wonder why sanding takes forever. Therefore, move in steady steps so each grit removes the previous scratches quickly. A simple progression could be 80 → 120 → 180 → 240 → 320 → 400 → 600, adjusted to your job. In other words, the goal is not “highest grit,” it is “clean scratch replacement.”

How to know when to move to the next grit

Stop and check under good light. Consequently, when the surface shows a consistent scratch pattern with no random deep lines, you can move up. But if you still see “tram lines” from a lower grit, do not advance yet, because they will print through later.

Dry sanding vs wet sanding

Dry sanding cuts faster and is easier to control in early prep. However, wet sanding can reduce loading and helps keep the surface cooler. Therefore, use wet sanding mainly for refinement, blending, and finishing, not for heavy leveling.

Don’t ignore backing pads and interface foam

The same grit can behave differently depending on pad firmness. For example, a hard block will cut flatter and reveal highs and lows, while a soft interface can follow contours and reduce edge burn. Likewise, the right pad can make your sandpaper grit guide feel “more forgiving” without changing the grit number.

Common grit mistakes that ruin results

Skipping grits is the big one. Consequently, it wastes time and leaves hidden scratches. Over-sanding edges is another, because thin areas show through first. Moreover, sanding without cleaning the panel between steps can drag grit contamination across the surface and create random deep scratches.

Building a reliable prep routine with the right supplies

A consistent routine is easier when you always have the right abrasives and coatings on hand. Therefore, Legacy Coatings keeps systems organized so you can pair abrasives, primers, and topcoats without guessing. You can explore our products for refinish and industrial needs, and you can review our services when you want support with choosing a full system. In addition, our partners help cover the tools and materials that keep workflows consistent, and Legacy Coatings stays available when you need the right match for substrate, coating type, and environment. For autobody clips, fasteners, and related shop essentials, you can also check Legacy Auto Supply.

FAQs

What grit should I use before primer?

Most importantly, pick a grit that gives adhesion without deep scratches. Therefore, 180 to 320 is common depending on the primer type and the surface condition, and a steady step-up afterward keeps the scratch pattern controlled.

What grit should I use before basecoat?

In many refinish jobs, 400 to 600 works well. However, if the primer is not level, stepping down to refine texture first can prevent mapping and patchy metallics.

Why do I still see scratches after paint?

Usually the earlier grit scratches were not fully removed, or the jump between grits was too large. Consequently, those deeper lines can telegraph through primer and color, especially under strong lighting.

Is wet sanding always better?

Not always. Therefore, dry sanding is often better for shaping and leveling, while wet sanding is helpful for finer grits, denibbing, and blending because it can reduce loading and keep heat down.

How can I avoid sanding through edges?

Use lighter pressure near edges, choose the right pad firmness, and avoid lingering in one spot. In addition, tape sharp body lines when needed and let the grit progression do the work instead of force.