How to Pick Abrasive Paper: a Sandpaper Grade

The short answer on abrasive paper

Here is the rule that governs most abrasive paper decisions: pick the grain for the material, the grit for the cut, and the backing for how the job is actually run. One number drives most of the choice, and that is the grit: in the FEPA or ISO 848 system a higher number means a finer grain, a shallower cut and a lighter scratch mark. P80 and P120 remove stock and open up a surface; P400 cleans up and prepares a face for coating; P1500 smooths a surface that is already close to final; P2000 and P3000 are the polish and cleanup band, the last light touches on a cured or nearly finished surface. Two scenarios where this rule bends: on very soft, sugary boards such as MDF, even a P400 or P80 face loads fast because the dust packs the grain, so a coarser grit with a moving pad beats a fine grit held in one spot; and on cured topcoats the rule inverts, because P2000 on paint is a de-raising pass, and running it too hard glazes the finish instead of smoothing it. If your work is everyday wood, panel or light metal finishing, start at P120 or P180, work down one step at a time, and confirm that the disc format fits your tool before you cut into stock. For the shapes we supply in paper form, look at the sanding disc range and the all abrasive products page, and keep the abrasives glossary open whenever a label term is unfamiliar.

Two habits turn this from guesswork into a repeatable spec. Always name the grit standard you are buying to, because a P120 on one scale is not a 120 grit on another; and always confirm the backing format, the disc size and the tool speed together, because a mismatch on any one of those three shows up on the part, not on the label. Everything below is the reasoning behind those two moves. The grit scale itself is explained plainly at the FEPA grit standard (ISO 848), and that one reference stops most mix-ups at the enquiry stage.

How abrasive paper actually works

Abrasive paper is a coated abrasive: a layer of cutting grain is bonded onto a backing, and on a disc that backing carries the whole build. Three variables decide how it behaves on the part, and they trade against each other more than most buyers expect.

Grain, grit and bond

Grain decides how the cut feels. The default grain for wood, painted surfaces and general metal work is aluminium oxide: it cuts a wide range of materials well, loads slowly and it is the economical grain, which is why it carries most of the range. The material properties behind that behaviour are a fair read at the properties of aluminium oxide.
Silicon carbide is the sharper, harder grain. It suits plastics, gel coats, composites and non ferrous metal, where it cuts a soft, slick material without packing. See the properties of silicon carbide.
Zirconia alumina is the tough, semi open grain for jobs that pack everything else: castings and heavy stock removal, where the face has to stay open.
Grit is the grain size, named on the FEPA or ISO 848 scale, and it sets how deep each pass cuts.
Bond holds grain to backing. A tighter bond keeps more grain on the sheet and runs the paper longer, at the cost of a slightly duller cut; a soft bond cuts fast and sheds grain sooner, which reads as a shorter life. In practice, the bond is the quiet variable that decides whether a grit you already know behaves the same on two different suppliers' paper.

The grit scale is a ladder, and it is worth memorising the rungs once:

The grit ladder

P24 – P40 🛠️ — rough stock removal, stripping, knocking down high material.
P60 – P120 ⚙️ — general removal and surface opening; the everyday band for most preparation.
P180 – P240 📏 — evening a face out, blending transitions, preparing for a primer or filler.
P320 – P400 ✅ — cleanup, pre-primer and pre-topcoat prep, de-raising rough marks.
P1500 – P2000 ✨ — fine polish band: the final smooth-down on a cured or nearly finished surface.
P2500 and finer — hand finishing and very light de-raising, mostly on cured coatings.

One habit saves money on every order: read the whole label, not just the grit. A typical disc label lists the grain, the FEPA grit, the diameter, the backing format and a maximum working speed where it is printed for that disc. The speed figure is the one people forget, so when it is not printed, the rule is simple — confirm the rated speed against the model and keep the tool below it. That habit will come back in the safety section, because the paper and the tool are the pair, not the paper alone.

The three decisions, grain, grit and backing, are made in that order. Match the grain to the material, set the grit to the cut, then choose the backing to suit how the job runs. Change one deliberately and keep the others fixed, or you end up solving three problems at once and not learning which one moved.

Backings, formats and grit availability

The grain and grit tell you what the paper does; the backing tells you how you run it. This is where most of the practical choice happens, so it deserves its own section.

Hook-and-loop (velcro) discs 🧵 — the default for random orbit and palm sanders. The disc swaps onto the pad in one tap, which is what makes a multi grit sequence possible at all: you move from P180 to P400 in one tool change instead of gluing and peeling. For a first run, start with a 5-inch format that matches a standard pad, and you can see exactly what that looks like on the 5-inch 8-hole hook-and-loop disc.
PSA (pressure sensitive adhesive) discs — a paper disc glued to a fixed sanding pad, common on stationary discs and dedicated pads. The glue is part of the build: a quality PSA face holds the disc flat, and a weak one lets the edge wander and chatter the part. The 4-inch PSA sanding disc page is a good reference for the format and the grits we run on it.
Mesh discs — cut into a mesh of short strips with a fine bond, which means dust passes through instead of packing the face. They are the pick on clog-prone, high-dust work: putty, some coatings, and soft materials that load an ordinary paper in minutes. Both the 5-inch and 6-inch mesh formats run the fine grits; see the 5-inch mesh sanding disc for that size.
Solid, non-hole discs — a flat, rigid disc with no ventilation holes, used where you want the whole face working evenly at once rather than letting dust escape. The 6-inch non-hole sanding disc is the format to look at for this.

Grit availability matters as much as the format itself. Our sanding discs run from P60 to P5000 across the 3-, 4-, 5- and 6-inch sizes, and the hook-and-loop line covers the same sizes in the same grit span. Two practical notes from the shop floor. First, the very fine grits past P1200 are where the range thins out, and the format list for P2000 and P3000 is shorter than for P180 or P400, so if you spec a fine grit, confirm the backing size you need is actually in the run. Second, in practice a P2000 job on a big surface works best on a 5-inch or 6-inch disc rather than a 3-inch one, because the finer the grit, the more you want area under the part to keep the whole face in one scratch band. The hook-and-loop sanding discs page shows the disc formats we list, and the sanding disc range is where the grit availability per size is confirmed.

The decision rule for backing: if you run a random orbit or a palm tool, go hook-and-loop; if you run a dedicated or stationary pad, go PSA; if the material clogs faces fast, go mesh; if you want the full face working without ventilation, go solid. That mapping, plus the grit, is the whole spec.

Choosing by material and finish line

The grit sequence is where abrasive paper either saves the job or ruins it, because every scratch pattern you leave is the one the next stage has to cover. The rule underneath everything is the same one flap disc work runs on: each step must be finer than the one before it. Skip a rung and the coarser scratch survives under the next coat and shows through.

Worked example: a hardwood floor panel, bare to satin finish

A 1.2 m by 2 m hardwood board, bare, going to a satin clear coat. Tool: a random orbit sander with 3-inch PSA discs across the whole sequence, working across the grain each step.

P80 — remove old finish and high spots, get the panel level. This is the step that takes real pressure; the P80 wants material movement.
P120 — open the grain and even out the P80 marks. Light pressure now; the board is level and the job is texture, not stock.
P180 — bring the whole surface into one even band. This is the step people skip and then fight at P400, because P180 is where the panel stops looking ground and starts looking prepared.
P240 — blend any transition and clean up ahead of primer.
P320 — the last abrasive pass before the first topcoat goes on.
P400 — between topcoats: skim the dried film, remove dust nibs and de-raise, so the next coat lays flat.
P1500 — after the final topcoat is cured, the first polish pass.
P2000 — the smooth-down on the cured surface. On hardwood it gives the surface the fine, even texture that a coat then lays over evenly, which is why a P2000 pass is standard on a floor before the final wax or top layer.

The thing that makes or breaks this sequence is the P400 step. A lot of floors that come out scratchy have skipped straight from P320 to P1500, and the P320 marks sit under the polish. Add the P400 back in and the surface clears. This is the single most common finish failure we see on floor work, and it is a sequence error, not a paper quality error.

Worked example: a softwood panel to primer and clear

Same panel, but softwood, going to primer and a satin clear. The sequence shifts because softwood dents, so pressure comes out of every step from P180 up:

P120 — bring the panel flat. Softwood is already near finish, so P80 is usually overkill and just deepens the dents.
P240 — prep the face for primer.
P400 — on the cured primer, light pass, then check: the primer should read as one uniform, low scratch, not a patchwork of P240 marks.
P1500 — first polish on the cured topcoat.
P2000 — final smooth-down.

The difference between the two sequences is not the grits so much as the pressure profile: hardwood takes the P80 hit and recovers, softwood takes the dent and keeps it. If you only ever run one of the two, the softwood one is the one to learn, because the pressure discipline on it transfers straight to panel and paint work, where there is no wood to hide behind.

Grit by material, a starting reference

MDF and engineered boards 🪵 — P80–P120 to remove, P240–P400 to bring it even. MDF loads a face fast because it is soft and sugary, so a coarser grit and a moving pad beat a fine grit held in one spot; on heavy dust, a mesh face keeps working longer.
Bare hardwood and softwood — P120–P180 to level, P320–P400 before coat, P1500–P2000 after cure, as walked through above.
Primed automotive panels ⚙️ — P400 and finer on cured primer or filler. Coarser grits on a primed panel are where the repair shows later, because the topcoat hides nothing below P400.
Cured topcoat — P1500 to P2000, lightest pressure of any line on the list, and the surface has to be dry. The automotive repair side of this sequence is covered in the automotive repair sanding use notes.
Mild steel and stainless surface prep — P80–P120 to prepare, P240 to clean up; this is where paper on a disc does the work, and the metal side is better served by the metal fabrication abrasive use notes and, for heavier removal, by flap work rather than paper.
Plastics, gel coats and composites — the sharper, harder grain is the pick here, with P240–P400 to even a gel coat and P1500–P2000 to de-raise; a soft, general grain on plastic loads and rubs more than it cuts.

The rule underneath all six lines is the same: match the grain to the material, then set the grit to the cut, and never let a coarser scratch survive into a finer stage.

Where P2000 earns its place

Because P2000 comes up in so many enquiries, it is worth treating on its own. P2000 is a fine grit, and its whole job is to de-raise a surface rather than remove stock. That means it is the pass you run after the heavy work is done, not the one you start with. Use P2000 to open up a surface that has micro scratches, to soften the marks left by a P400, and to bring a part to a state where a clear coat or a fine film will sit evenly. A lot of the value in P2000 is that it keeps the whole surface in one band of texture instead of leaving deep scratches that the next stage has to fight.

Where P2000 does not belong is as a first pass. If you start on P2000 over P400 scratches or filler texture, you are asking a fine grit to do a coarse grit's job, and it will glaze and load instead of cutting. P2000 rewards a clean sheet, light pressure and a moving pad. Pressing into it is the opposite of what it wants; the fine grain wants to skim, not dig. On cured paint, P2000 is the classic last touch before the surface is judged, and it is why a P2000 sheet in the drawer shows up in most repair shops' workflow. If you only have one fine grit and you are unsure, P400 does more of the real prep and P2000 is the polish on top. That is a 2000 grade doing its one honest job: a final skim on a surface that is already there, not a removal pass. The grit availability for P2000 in each backing size is confirmed on the sanding disc range page, and the request a quotation form is where you confirm P2000 is in the run for your size.

Wet sanding vs. dry sanding

Some fine grits ship in two grades that look the same on the shelf but behave differently under water: a dry grade, made for dry sanding with dust extraction, and a wet-dry grade, with a bond and paper that tolerate water and hold grain through a wet rub. P2000 is one of the grits commonly listed as a 2000 grade in both forms, and it is where a buyer most often orders the wrong grade and then wonders why the sheet fell apart.

Dry grade, dry use — the default for wood, panel and general prep. It wants dust extraction, not water; running it wet softens the bond and the face sheds early.
Wet-dry grade, wet use — the pick for cured coatings, plastics and the fine de-raise on a wet face. Water cools the work, carries the dust off the pad and keeps the fine grain from glazing, and the grade is built to take it.
Wet-dry grade, dry use — works in a pinch, but a 2000 grit face made to flex and drain can load differently than a dry grade of the same grit, so the scratch band can read slightly coarser.

Two habits stop the failure. First, name the grade type in the order: the grit tells you the cut, and the grade tells you whether the paper takes water. Second, when you wet-sand, plan the water side: a way to rinse the pad face, a way to dry the part before the next stage, and no water wicking into a panel edge. When you are unsure which grade to run, confirm the grade type with sales, and on a request a quotation conversation it is a one line field on the spec.

Speed, dust and safety

Paper work on a hand block is low risk; paper on a spinning pad is a different animal, and it is the spinning part that needs the safety habits. This section is the one to hand a new hire before they run a sander.

The speed side first. The governing number is the maximum working speed, and on coated products it is a property of the disc, not the tool: surface speed is diameter times RPM, so a bigger disc on the same sander reaches a higher speed than a smaller one. A 6-inch disc on a given machine runs faster in linear terms than a 3-inch one on the same machine, which is why the same tool can be fine with one disc size and too fast for another. The working method is short: run the tool at no load, measure the pad speed, work out the surface speed for the disc you are fitting, and keep it below the printed maximum. Where the disc does not print a maximum for that size, the rule is to confirm the rated speed against the model and keep the tool below it. The U.S. portable power tool rules are at OSHA 29 CFR 1910.244 — portable power tools, and they are worth a read before a team runs a tool off the standard pad.

The PPE side next. Eye and face protection goes on for every pad operation, not just the coarse grits, because a spinning disc that sheds or a particle off the part is the hazard. For dust, the load drives the requirement: a P80 pass on MDF throws a fine, high volume dust that is the worst case on a wood shop floor, and a P2000 pass on cured paint throws a coating dust that behaves differently. The general PPE requirements are a useful baseline at OSHA 29 CFR 1910.132 — PPE general requirements, and a plain reading of abrasive wheel and disc setup is at CCOHS: Abrasive Wheels. Send both to the team before the first run.

Dust is the part people under-plan, and it deserves its own line because it is where the long term exposure lives. Three things do most of the work: extraction that actually reaches the pad, a dust class that suits the material, and a waste habit that does not sweep to the corner. The dust topic is covered plainly at abrasive dust and airborne particulates, and it is the link to keep open when someone asks which mask fits a given grit and material, because the answer changes with the load.

Two failure modes are worth naming because they start at the label, not at the operator. A disc run past its speed rating can delaminate and shed at the edge, and a disc seated on a wrong or undersized pad face can walk and catch. Both are preventable, and both come back to the same two habits: read the disc, read the tool, and only then start the job.

Cost, life and lead time

On cost, people usually buy the cheapest sheet per unit and end up paying for it in machine time. A face that cuts clean and wears even does more per sheet than a cheap face that loads fast, so the cost per finished surface is often lower on the better paper, and the difference shows up in how many parts you get between paper changes. For a job with steady volume, the wear rate and the cost per finished surface matter more than the sticker price. That is the number a hook-and-loop sanding discs conversation should be built around, because at volume the per part cost is where the saving actually lands.

A useful comparison for two papers you are choosing between: cost per finished surface, not cost per sheet. If paper A costs more but the sheet lasts three times as long over the same job, the finished surface is cheaper on A. That is the number to ask a supplier to help you with, and it is the one that flips when you compare a cheap P400 face against a good one, or a P2000 face against a P3000 polish sheet.

On lead time, two things set it. In stock grits and common sizes ship fast; off grid grits or a backing you do not hold in the same run take longer, because the grain, the backing and the format all have to line up. For private label work, add time for the label, the packing and any spec sheet you want on the box. The private label service page explains what we can put on the packaging and how minimum order quantities work; confirm the MOQ and lead time with sales before you build the run around a date, because the fine grits and the branded packing are the two things that stretch a lead time the most.

Storage and transport matter more with paper than with a disc, and they are where a good paper quietly goes bad. Rolls and sheets curl when they take humidity or heat, a crushed edge stays crushed, and a face that has been damp can let the bond go soft before the job is even run. The practical read: store paper flat and dry, keep the roll or the stack out of direct sun, and check a face for delamination at the edge before you trust it on a part you care about. A paper that curls out of the bag is telling you something about the trip it just took, and that is a storage and transport check, not a defect in the grain.

The short version for a planning conversation: name the grit, the grain, the format and the size, and ask two numbers back. One is the cost per finished surface at your volume, and the other is the lead time for a repeat run. Those two are the ones that decide the buy, and both are straight answers, not estimates, once the spec is named.

Common mistakes and how to fix them

The fixes here are usually cheaper than the mistakes. This is the list to run when a surface comes out wrong, in the order the causes show up most often:

Skipping grits. Going from P80 straight to P400, or from P400 to P2000, leaves the coarser scratch under the finer stage, and the finish shows it. The fix is the intermediate step, one rung at a time, so each scratch pattern is finer than the one it covers.
Pressing too hard. Paper is not a flap disc; it loads and glazes when you lean in, and on softwood it dents instead of cutting. Lighter pressure and a moving pad are the fix, not a coarser grit. The grit was right; the technique was not.
Edge peel and delamination. A face that peels at the edge, or a disc that crinkles, is usually storage and transport damage or a run past the rated speed. The fix is flat, dry storage, the correct speed, and fresh paper on the critical pass.
Pad and disc mismatch. A round PSA disc on a flat pad wanders at the edge and chatters the part; a hook-and-loop disc on a worn pad face loses grip and the disc skids. The fix is a clean, matched pad, and on a worn hook-and-loop face, a new pad rather than a new disc.
Wrong grain for the material. Aluminum oxide on plastic or gel coat rubs and loads; silicon carbide is the grain for those, and that is the fix when the finish comes out dull instead of clean. Match the grain to the material first, then talk grit.
Wet-dry on a dry-grade face. P2000 and finer are often wet-dry grades, and running a dry-grade fine paper with water is what ruins the bond. Confirm the grade type with sales before you wet-sand, and the reverse is just as true: a wet-dry face used bone dry can load differently than the same grit on the dry grade.
Reading the grit without the standard. A P240 that is really an older scale 240 is a different cut, and the surface will show the gap. The fix is naming FEPA or ISO 848 in every enquiry, so the grit you specify and the grit that ships are the same grit. The reference is at the FEPA grit standard, and the all abrasive products page shows the range we spec on.

The thread through all seven is the same one the whole article runs on: most of the complaints are match complaints wearing a grit's name. Fix the grain, the grit, the backing or the technique, and the surface comes back. The abrasives glossary keeps the terms straight so you and the team are diagnosing the same problem, and the sanding disc range is where the grain and grit you need are confirmed against your format.

FAQ

Can I skip from P80 to P2000 on a panel? No, and it is the failure behind most scratchy finishes. Every skipped rung leaves its scratch under the next stage, so a P80-to-P2000 jump puts P80 marks under a P2000 polish and the topcoat shows them. Add the intermediate rungs, one step at a time, and the surface clears.

What grit do I start with for bare wood? In many cases P80 to P120, depending on how much the panel needs. P80 for old finish and level work, P120 for a surface that is already near level, and P180 to even out before the fine work. The material and the starting condition set the opening grit, not a fixed number.

When do I use P2000? P2000 is the final polish and de-raising grit, on a cured topcoat or a surface that is already close to final. On a cured paint face it is the last light pass before the surface is judged; on bare wood it is the smooth-down ahead of the final wax or top layer. It is never the first grit on a raw surface.

What grit standard should I name in an enquiry? FEPA or ISO 848, plus the grit, the grain, the format and the size. That keeps the order from being mixed with a different grit scale, and it is the habit that stops the wrong cut arriving at the bench. The scale is explained at the FEPA grit standard (ISO 848).

Is aluminum oxide always the grain I want? No. Aluminum oxide is the default on wood, painted surfaces and general metal prep, and it is the economical all rounder. When the material is plastic, a gel coat, a composite or a soft non ferrous metal, the harder, sharper grain is the pick, because it cuts that slick material without packing. The two property pages, aluminium oxide and silicon carbide, are the quick read on why the two behave differently.

How much paper should I plan per part? Plan by cost per finished surface, not by sheet count, because a face that lasts longer costs less per surface even at a higher sheet price. For a regular run, confirm the wear rate and the minimum order with sales against your volume, and the private label service page is where a branded or standing order conversation starts.

Before you buy

A short compliance and purchasing checklist. This is a reminder, not a substitute for your own site rules, and in compliant use with the right protection the risk of these tools is reduced but not zero.

Confirm the tool pad speed and the disc surface speed: run the tool at no load, work out the surface speed for the size you are fitting, and keep it below the printed maximum working speed. Where a disc does not print a speed for that size, confirm the rated speed against the model.
Check the backing format and the pad face match, and that the disc sits fully and flat on the pad; a wrong or undersized pad is the setup behind most edge chatter.
Fit and keep the guard or shroud on the tool where the design has one, and make sure the work holds firm before the pad goes on.
Wear eye and face protection on every pad operation, and match the respiratory protection to the dust load of the grit and material you are running.
Run dust extraction that actually reaches the pad, with a filter that suits the material, and a waste habit that does not sweep to the corner.
Name the grit standard (FEPA or ISO 848), the grain, the format and the size in every order, so the grit you specify and the grit that ship are the same grit.
Check the certificate or inspection report you rely on for the run, and the storage and transport state of the paper before you trust a face on a part you care about.
Follow the maker's install and handling notes, and for a hook-and-loop sanding discs or OEM & private-label service order, confirm the MOQ, the packing and the lead time with sales through the request a quotation page.

If you tell us the material, the finish you are aiming for and the tool you run, we can help you pick the grit, the grain and the backing to start from, and we will pre-select a sequence against it on the request a quotation page. Send the three and we will work the grit ladder with you from P120 to the P2000 finish.