Sandpaper Grit Guide: Types, Sizes & Selection

Jun 27, 2026 AIMS Industrial Supplies

Walk into any hardware store and you'll find sandpaper labelled 40, 80, 120, 240, 400, 2000 — sometimes with a P in front of the number, sometimes without. No explanation of what those numbers mean, what the P indicates, or why two packs labelled "400 grit" from different brands can produce visibly different results on the same surface.

This guide explains the system — grit numbers, abrasive minerals, backing materials, and the sequences that produce the right result for the job in front of you.

Sandpaper Grit Quick Reference — FEPA, ANSI & Particle Size

The table below covers both grading systems used on sandpaper sold in Australia and the United States, with approximate particle sizes from ISO 6344 (FEPA P-grade). Use it to convert between systems or to identify the right grade for your task at a glance. Detailed explanations of each system — and why they diverge at fine grades — follow below.

Grade band	FEPA P-grade (AU standard)	ANSI/CAMI (US) approx.	Particle size (µm)	Typical use
Extra coarse	P12–P36	12–36	1,815–525 µm	Heavy material removal, shaping, stripping paint or varnish, floor sanding first pass
Coarse	P40–P60	40–60	425–260 µm	Rapid stock removal, levelling cupped timber, removing mill scale from steel
Medium	P80–P120	80–120	200–125 µm	General sanding, dimensioning, removing previous grit scratches
Fine	P150–P240	150–220	100–58 µm	Finishing bare timber or metal prior to coating, final hand-sand pass
Very fine	P280–P400	240–360 ⚠	52–30 µm	Between-coat keying, final bare-surface prep, light surface levelling
Extra fine	P600–P1200	400–600 ⚠	25–15 µm	Wet sanding primer and base coats (automotive)
Super fine	P1500–P2500	1000–1500 ⚠	12.6–8.4 µm	Wet sanding clear coat and lacquer
Ultra fine	P3000–P5000	2000–3000 ⚠	6.5–3.5 µm	Pre-polish automotive finishing, removing fine swirl marks

⚠ ANSI/CAMI grades above P220 / CAMI 220 are approximate only. The two systems diverge significantly at fine grits. At P280 and finer, ANSI grade numbers no longer correspond to the same particle size as the equivalent P number. CAMI 400 ≈ P800 — a CAMI 400-labelled product is far finer than a P400 product. See the full comparison table below.

What the grit number means

The grit number refers to the number of abrasive particles per square inch on the sandpaper surface — determined by the mesh size used to sieve and grade the abrasive particles. A higher number means smaller particles were passed through a finer mesh. Smaller particles cut less aggressively and leave a smoother surface.

Higher grit = finer abrasive = smoother finish. Lower grit = coarser abrasive = faster material removal.

This trips up beginners consistently. "Higher" feels like it should mean coarser, because higher-grit tools (angle grinders, drill speeds) are associated with more power. Sandpaper works the opposite way.

Grade	FEPA P-grade	ANSI/CAMI approx.	Particle size	What it does
Extra coarse	P24–P36	24–36	~900–525 µm	Heavy material removal, shaping, stripping paint or varnish from flat surfaces
Coarse	P40–P60	40–60	~425–260 µm	Rapid stock removal, levelling cupped timber, removing mill scale from steel
Medium	P80–P120	80–120	~200–125 µm	General sanding, dimensioning, removing previous grit scratches
Fine	P150–P180	150–180	~100–80 µm	Finishing bare timber or metal prior to coating
Very fine	P220–P280	220–240 ⚠	~58–52 µm	Final bare-surface prep, first coat keying
Ultra-fine	P320–P400	280–360 ⚠	~36–30 µm	Between coats, final bare-timber finish, light surface levelling
Super-fine	P600–P1000	400–500 ⚠	~25–18 µm	Wet sanding primer and base coats (automotive)
Micro-fine	P1200–P2000	600–1000 ⚠	~15–8.4 µm	Wet sanding clear coat and lacquer
Ultra-micro-fine	P2500–P5000	1500–3000 ⚠	~8–3.5 µm	Pre-polish automotive finishing, removing fine swirl marks

⚠ ANSI/CAMI grades at P220/CAMI 220 and finer are approximate equivalents only. The two systems diverge significantly at fine grits — see the comparison table in the next section.

Particle sizes above are approximate mean values per ISO 6344 (FEPA P-grade). FEPA P-grades are the standard for all coated abrasives (sandpaper, sanding discs, belts) sold in Australia.

The two grit systems: CAMI and P-grade (FEPA)

There are two grading standards for sandpaper abrasives in common use: CAMI (Coated Abrasive Manufacturers Institute — North American standard) and P-grade (FEPA — Federation of European Producers of Abrasives, the international standard used in Australia). Most abrasives sold in Australia are labelled in P-grade. CAMI grading still appears on some imported US-brand packs and older workshop stock.

At coarse grits, the two systems are nearly identical. At fine grits, the gap becomes significant:

CAMI grit	P-grade (FEPA) equivalent	Particle size (µm)	Practical note
40	P40	~425 µm	Near-identical
60	P60	~260 µm	Near-identical
80	P80	~200 µm	Near-identical
100	P100	~150 µm	Very close
120	P120	~125 µm	Very close
150	P150	~100 µm	Very close
180	P180	~80 µm	Close
220	P220	~58 µm	Close — last grade where they're comparable
240	P280	~52 µm	Begins to diverge
280	P320	~36 µm	Noticeably finer P-grade
320	P400	~30 µm	Significant gap
400	P800	~15 µm	Large gap — CAMI 400 is far coarser than P400
600	P1200	~6 µm	Large gap

⚠️ Important: If a finishing specification calls for P400 (a common between-coat abrasive for automotive refinishing), using a CAMI 400-labelled pack instead gives you the equivalent of P800 — far finer than required, at higher cost. Conversely, using CAMI 320 when P320 is specified gives you roughly P400 — finer than intended. Check the label. P-grade will have the "P" prefix; CAMI is the number alone.

FEPA vs ANSI — why two systems exist

The FEPA P-grade system and the CAMI system evolved independently on different continents, each standardised by its own industry body before international alignment became practical.

FEPA P-grade is defined by ISO 6344 (Parts 2 and 3) — the international standard for coated abrasives. ISO 6344-2 covers macrogrit grades P12–P220; ISO 6344-3 covers microgrit grades P240–P5000. These standards specify precise mean particle diameters, sieve distributions, and tolerance bands. "P" stands for Papier — the German word for paper, reflecting the standard's European origin. FEPA P-grade is used throughout Australia, Europe, and most of Asia.

CAMI (Coated Abrasive Manufacturers Institute) is the North American equivalent, defined by ANSI B74.18. At coarse grades, CAMI and FEPA P were developed in parallel and produce essentially the same particle sizes. The divergence at fine grades arose because the two standards use different sieving methodologies and statistical distributions to define particle size at fine grades — resulting in systematically different physical sizes for the same grade number above CAMI 220 / P220.

The practical takeaway: In Australia, FEPA P-grade is the default. All Klingspor, Norton, Pferd, and 3M products sold through AIMS Industrial are P-grade labelled. If you are working from a US specification or using US-sourced finishing guides, verify whether grit numbers cited are CAMI or P-grade — particularly for any grade above 220.

When micron grades replace grit numbers

At very fine grades (P1200 and finer), some industries and product lines describe abrasive grades in microns (µm) directly rather than using a grit number. This is common in:

Precision engineering and lapping: lapping films for valve seats, fuel injectors, and bearing surfaces are often specified in microns (e.g. 3 µm, 1 µm, 0.3 µm) — finer than the P5000 end of the FEPA grit scale.
Optical and lens polishing: micron and sub-micron abrasive films are the standard. Grit numbers are not used.
Premium automotive finishing compounds: some polishing compounds specify particle size in microns (e.g. "3 µm compound") rather than a grit equivalent. These products are technically beyond the sandpaper grit scale and should not be compared directly to P-grade sandpapers.
Metallographic sample preparation: laboratory polishing of metal specimens for microscopy uses micron-rated abrasive papers from P600 down to sub-micron diamond films.

For most trade and workshop use, micron grades are not relevant — the P-grade system covers everything from floor sanding through automotive clear coat finishing. Micron-rated products come into play only at the precision-engineering end of the application spectrum.

ℹ P-grade to micron conversion (reference): P600 ≈ 25 µm | P800 ≈ 15 µm | P1000 ≈ 18 µm | P1200 ≈ 15 µm | P1500 ≈ 12.6 µm | P2000 ≈ 10 µm | P2500 ≈ 8.4 µm | P3000 ≈ 6.5 µm | P5000 ≈ 3.5 µm. Values are approximate mean particle diameters per ISO 6344-3.

Abrasive minerals

The abrasive particle determines how the paper cuts, how long it lasts, and what surfaces it suits. Five minerals are in common use on coated abrasives available in Australia:

Mineral	Colour	Properties	Best applications
Aluminium oxide (AO)	Brown/red	Tough, self-fracturing (new cutting edges exposed as particles break), durable under heat, long life	Timber (all types), mild steel, cast iron, general metal finishing, drywall/plasterboard, paint
Silicon carbide (SiC)	Black/dark grey	Harder and sharper than AO, more brittle, excellent on hard/non-ferrous surfaces, ideal for wet use	Wet sanding automotive clear coat and lacquer, glass, ceramics, stone, hard plastics, non-ferrous metals (aluminium, copper, brass)
Garnet	Orange/red	Natural mineral, soft, fractures quickly (not long-lasting), produces extremely smooth finish on timber	Final hand-sanding on bare timber (furniture, joinery) before stain or oil; not suited to power sanding or metal
Zirconia alumina	Blue/green	Very aggressive, extremely heat-tolerant, long life under heavy loading	Heavy metal stock removal on belt sanders and angle grinder flap discs — not common in hand-sheet form
Ceramic alumina	Purple/grey	Hardest common abrasive mineral, self-sharpening, exceptional life in premium grades	High-speed belt sanding, industrial metal fabrication; premium products only — overkill for most general use

Practical note for most users: Aluminium oxide is the default for wood and general metal work. Silicon carbide is the correct choice for wet sanding and non-ferrous metals. Garnet earns its place for final bare-timber hand sanding where the smoothness of the finish justifies the shorter life. You will rarely need zirconia or ceramic in sheet form — those minerals are most useful in high-speed belt and disc applications.

For hook-and-loop sanding disc and fibre disc selection (with the abrasive grain golden rule by metal type), see our Sanding Disc & Abrasive Disc Guide. For overlapping flap disc abrasives, see our Flap Disc & Abrasive Guide — the selection logic for grinder applications is different.

Abrasive mineral vs grit — what matters more

Both the mineral and the grit number determine performance, but they affect different things:

Grit number determines the coarseness of the cut and the surface texture left behind. A P120 silicon carbide paper and a P120 aluminium oxide paper remove material to the same scratch depth — the grit controls that.
Mineral type determines the cutting mechanism, life expectancy, and suitability for the material being sanded. Silicon carbide at P120 cuts glass and ceramics efficiently; aluminium oxide at P120 is better on timber and steel.

The common error is substituting one mineral for another at the same grit and expecting identical results. On non-ferrous metals, aluminium oxide loads quickly (the swarf sticks to the abrasive). Silicon carbide at the same grit clears swarf more effectively. On timber, silicon carbide is sharper but less durable — it fractures more readily and wears faster than aluminium oxide on fibrous surfaces.

When selecting sandpaper: choose grit number for the required surface finish; choose mineral type for the material and application conditions.

Backing materials

The backing is what the abrasive is bonded to. It determines flexibility, tear resistance, heat tolerance, and whether the paper can be used wet. Backing weight is denoted by a letter.

Backing type	Weight/grade	Properties	Applications
Paper — A weight	Lightest	Most flexible, tears easily under hard use	Fine hand sanding (P150–P400), sanding blocks, finish work
Paper — C/D weight	Medium	Standard general-purpose weight, good balance of flexibility and durability	Most orbital and random orbital sander applications, general workshop use
Paper — E weight	Heaviest paper	Stiff, durable, resists tearing under aggressive work	Coarse grits (P24–P60) for heavy stock removal on belt sanders
Cloth — J weight	Flexible cloth	Wraps around contours without cracking, more durable than paper	Curved surfaces, detail work, portable belt sanding on irregular shapes
Cloth — X weight	Heavy cloth	High tensile strength, handles heat well, long life under continuous belt running	Stationary belt sanders, drum sanders, industrial belt applications
Film (polyester)	Consistent	Dimensionally stable, uniform thickness, suitable for wet use, non-absorbent	Automotive wet sanding (fine grits P800–P3000), premium finishing applications
Foam/sponge	Variable	Conforms to complex curves and moulded profiles, compressible	Mouldings, furniture profiles, contoured surfaces; hand use only
Mesh/net	Open weave	Open structure allows dust to pass through the backing, significantly reduces loading	Plasterboard, resinous timber, and any application where dust clogging is a problem; requires a compatible dust-extraction sander

ℹ Can I use any sandpaper wet? No. Only silicon carbide on film or specifically rated waterproof paper backing is suitable for wet use. Standard aluminium oxide on A or C weight paper backing will absorb water and disintegrate within seconds of contact. Check the product label — waterproof grades are explicitly marked.

Grit selection quick reference by application

A condensed selection guide for common Australian trade and workshop applications. Full grit sequences for each application are in the detailed sections below.

Application	Starting grit	Finishing grit	Mineral	Notes
Bare timber — furniture / joinery	P80–P120	P180–P220	Aluminium oxide or garnet (final pass)	Sand with grain on final pass; raise grain before water-based topcoat
Timber floors — first cut	P40 (diagonal pass)	P100–P120	Aluminium oxide	Match edge-sander grit to belt sander grade
Between paint / varnish coats	P320	P400	Aluminium oxide	Light touch, sanding block on flat surfaces; degloss only
Mild steel — prep for primer	P80	P240	Aluminium oxide	Do not finish finer than P240 — adhesion decreases on very smooth steel
Stainless steel — brushed finish	P120–P150	P150 (consistent direction)	Aluminium oxide or ceramic	Unidirectional strokes only; no random orbital
Stainless steel — mirror polish	P180	P1200 → buffing compound	Aluminium oxide / silicon carbide (fine)	Each grade must fully remove previous scratches before progressing
Aluminium	P120	P240–P320	Silicon carbide or AO with stearate coating	Standard AO loads quickly on aluminium; use lubricated or SiC
Automotive — orange peel correction	P1200–P1500 wet	P3000 wet → polishing compound	Silicon carbide (waterproof backing)	Water lubrication essential; film or waterproof backing only
Automotive — between primer coats	P400–P600 dry	P600–P800 wet	Silicon carbide (wet) / aluminium oxide (dry)	Allow panel to dry fully after wet sanding before recoating
Plasterboard — joins and fill	P120	P180–P220	Aluminium oxide	Avoid cutting through paper facing; moderate pressure only
Glass, ceramics, stone	P120–P180	P400–P800 (wet)	Silicon carbide	Wet sanding recommended; dry ceramic dust is a respiratory hazard

Sandpaper forms

The physical format of the sandpaper must match the tool and the task. Using the right abrasive mineral in the wrong form is a common source of poor results and wasted material.

Form	Common sizes (AU)	Use with
Sheet	230 × 280mm (standard AU size)	Hand sanding blocks, folded by hand for detail work. Design allows folding and tearing into halves, thirds, or quarters.
Roll	Widths 50–300mm, cut to length	Bench sanding, drum sanding, wrapping around custom profiles. Workshop standard for cutting custom lengths.
Hook-and-loop disc	115mm, 125mm, 150mm	Random orbital sanders, detail sanders. Velcro-style attachment. Must match the sander's pad diameter exactly.
PSA disc (pressure-sensitive adhesive)	150mm, 200mm	Orbital sanders with PSA pads. Peel-and-stick backing. Less common in AU than hook-and-loop.
Belt	75 × 533mm, 100 × 610mm (most common AU)	Portable belt sanders (check your tool spec — belt size is not universal), stationary belt grinders. Must match the tool's drive roller dimensions.
Sponge/block	Hand-held	Contoured surfaces, mouldings. Available dual-grit (different grades on each face). Not suitable for power tools.

Note on flap discs and grinding discs for angle grinders: These are covered separately in our Flap Disc & Abrasive Guide. The selection logic, safety requirements, and abrasive performance at grinder speeds are substantially different from the sheet, roll, and disc applications covered here.

Grit sequence guide: bare timber

Timber finishing is where grit sequence discipline matters most. Each grit removes the scratch marks from the previous grit. If you skip a grade, you leave deeper scratches in the surface that become visible — often dramatically so — once stain, oil, or clear coat is applied.

Standard bare timber sequence (furniture, joinery, cabinetry)

P80 → P120 → P180 → P220

Start at P80 if the surface has rough spots, milling marks, or light cupping. For pre-surfaced timber with minimal defects, starting at P120 is appropriate. Do not go below P80 on power tools unless you are genuinely shaping material. Finish at P220 before applying any water-based finish, stain, or oil. For oil-based finishes, P180 is often the finishing grade — coarser scratches give the oil more surface area to penetrate.

Between coats of paint or varnish (timber)

P320–P400 (very light touch)

The purpose is to knock back grain raise and minor dust nibs — not to remove material. Use a sanding block for flat surfaces. Work with the grain. Vacuum and wipe with a tack cloth before recoating.

Timber floors (drum sander)

First cut on badly cupped or heavily finished boards: P40 at a slight angle across the grain. Second pass along the grain: P60–P80. Final belt pass: P100–P120. Always hand-sand the edges with a matching grade — floor edge sanders are a common source of visible circular scratches that the drum doesn't reach.

Softwood vs hardwood

Softwoods (pine, radiata) raise grain more aggressively under water-based products. After P220, raise the grain deliberately with a damp cloth, let it dry, then lightly resand at P220 before applying the first coat. This avoids a rough surface after the first water-based coat.

Grit sequence guide: metal

Metal sanding has two distinct end goals: surface preparation for coating (paint, powder coat, or plating), and surface finishing for appearance (polished, brushed, or mirror finish). The sequences are different.

Mild steel — surface prep for paint

P80 → P120 → P180 → P240

Start at P80 to remove mill scale, rust, and old coating. Progress through the grades. Finish at P240 minimum for primer adhesion — a surface that is too smooth (finer than P240) can reduce paint adhesion. After sanding, remove all abrasive residue before priming.

Stainless steel — surface finishing

Stainless steel is typically worked to a specific surface finish designation. The most common:

Brushed/satin (2B equivalent): P120–P150 with a constant unidirectional stroke using an aluminium oxide or ceramic belt. Direction must be consistent — random or orbital marks are visible on stainless.
Mirror/polished: P180 → P240 → P320 → P400 → P600 → P800 → P1200, then buffing compound. Each grade must fully remove the previous grade's scratches before progressing.

Cross-contamination warning: Do not use the same abrasive on mild steel and stainless steel. Iron particles embedded in the abrasive will contaminate the stainless surface and cause rust staining within days. Keep separate sandpaper for stainless, clearly labelled.

Aluminium

Aluminium loads standard aluminium oxide paper quickly. Use silicon carbide paper or aluminium oxide with a stearate (anti-loading) coating for aluminium. Dry sanding aluminium creates fine, highly flammable dust — good dust extraction is essential. For wet sanding aluminium, silicon carbide on film or waterproof backing is the standard choice.

Cast iron

Aluminium oxide handles cast iron well. Cast iron dust is fine and dark — a nuisance and a contamination risk on other surfaces. Sand in a controlled area and clean up thoroughly before moving to other materials.

Grit sequence guide: automotive paint and clear coat

Automotive wet sanding is a distinct discipline from workshop or furniture sanding. The goal is to level orange peel texture in clear coat (or colour coat) before polishing to a high gloss. All sanding at these grades is done wet — water is the lubricant and swarf-clearing agent.

Correcting orange peel in clear coat

P1000–P1500 (wet) → P2000 (wet) → P3000 (wet) → polishing compound

Start at P1000–P1200 to flatten the orange peel texture. Progress to P1500 to refine the P1000 scratches. Move to P2000 to prepare the surface for polishing. P2500–P3000 is used for final scratch refinement before machine polishing. Each grade should fully eliminate the previous grade's scratches before progressing — hold the surface at a 45° angle under direct light to check.

Levelling a paint run

Feather the run with P800 or P1000 (wet) to level without cutting into adjacent good paint. Progress through P1200 → P1500 → P2000, then polish.

Sanding between primer coats (automotive)

P400–P600 (dry) or P600–P800 (wet)

Keying between primer coats: P400–P600 dry is standard. Wet sanding with P600–P800 is used where a finer surface is needed before colour coat. After wet sanding, allow the panel to dry fully (minimum several hours) before recoating — trapped moisture under paint causes blistering.

ℹ Paper choice for automotive wet sanding: Use silicon carbide on film backing or specifically marked waterproof paper (often labelled "wet or dry"). Standard paper-backed products disintegrate when wet. The 2000 grit and 3000 grit products widely available through automotive suppliers in Australia are typically silicon carbide on film or waterproof paper. Check the label before using.

Grit guide: plaster, render, and pre-paint prep

Plasterboard (drywall) and wet-applied plaster have specific requirements. The surfaces are relatively soft, they clog abrasives quickly, and the dust is fine and heavy — extract it or it goes everywhere.

Plasterboard joins, set, and fill

P80–P120 to level, P180–P220 final pass

Sand set and fill with P120 to level without cutting into the board paper facing. Move to P180–P220 for the final pass before priming. Sanding through the paper facing on plasterboard (visible as a fuzzy surface) creates a weak spot under paint — reduce pressure and check frequently.

Wet-applied plaster and render

P60–P80 (coarse imperfections), P120 final

Render is harder than plasterboard compound — it can handle more aggressive starting grits for levelling runs or trowel marks. Do not use a power sander on fresh, soft plaster — let it cure fully first. Hand sanding with a block is standard for most plaster work. P120 before priming is typically sufficient for render.

Keying a painted surface for recoating

P220–P320 (light scuff)

The objective is deglossing to improve adhesion, not material removal. A light pass with P220–P320 scuffing paper is sufficient for most interior paints. Liquid sandpaper (chemical deglosser) is an alternative for this step — see below.

Wet and dry sandpaper

"Wet and dry" is a specific product designation — not a description that applies to all sandpaper. Wet and dry paper is silicon carbide abrasive on a waterproof backing (film or resin-treated paper) designed for use with water as a lubricant. Water keeps the surface cool, prevents the abrasive from loading with swarf, and floats away the removed material so it does not re-scratch the surface.

When to use wet and dry paper:

Automotive clear coat and lacquer finishing (P1000 and finer)
Glass edge polishing
Ceramic and stone surface finishing
Non-ferrous metals (aluminium, brass, copper) where a wet process is preferred

When not to use wet and dry paper:

Timber — water raises the grain and can cause swelling and staining
Bare steel — water causes surface rust within hours
Anywhere you cannot manage the water and resulting slurry safely

Liquid sandpaper (chemical deglosser)

Liquid sandpaper — sold under brand names including Intergrain, Dulux Prep, and similar — is not abrasive. It is a solvent-based chemical that etches a glossy painted surface to improve adhesion for the next coat, without mechanical sanding. It removes the gloss chemically. It is useful for surfaces with complex profiles where hand-sanding is impractical, or as a preparation step on sound paintwork in good condition. It does not level imperfections, fill grain, or replace sanding on bare timber or heavily weathered surfaces.

Sanding discs for random orbital sanders: sizing and attachment

Random orbital sanders (ROS) produce a random oval orbit that prevents the circular scratch marks left by standard orbital sanders. They are the standard choice for furniture, cabinet, and automotive panel finishing. Getting the disc size and attachment type right is critical — the wrong size disc will not attach correctly and can detach under load.

Disc sizes in the Australian market

115mm: Quarter-sheet orbital sanders and some small detail sanders
125mm: Common on mid-size random orbital sanders (Bosch, Makita, Milwaukee 5" range)
150mm: Larger random orbital sanders, standard for automotive bodywork and cabinet finishing

The disc diameter must match the sander pad diameter exactly. Using a 125mm disc on a 150mm pad leaves the edge unsupported and the disc will tear. Using a 150mm disc on a 125mm pad is a safety risk — the overhanging edge can catch on the workpiece.

Dust extraction holes

Most random orbital sander discs have a hole pattern that aligns with the sander's dust extraction ports. Common patterns include 6-hole, 8-hole, and 15-hole (Festool Rotex/ETS compatible). Using a disc with a non-matching hole pattern on an extraction sander does not damage anything, but dust extraction performance will be poor. For mesh/net discs, extraction is through the open backing itself and standard holes are not required.

Hook-and-loop vs PSA

Hook-and-loop (Velcro-style): The dominant attachment method in AU. The disc has a loop backing; the sander pad has a hooked surface. Discs can be removed and replaced quickly and are repositionable. Standard for workshop and automotive use.

PSA (Pressure-Sensitive Adhesive): Peel-and-stick. Once applied, the disc is fixed until removed — removal is more difficult and the adhesive backing can leave residue on the pad. Less common in Australia than hook-and-loop, but still found on some older sanders and certain production finishing applications where disc migration is a concern.

The one mistake that ruins a finish: skipping grits

Each grit leaves a characteristic scratch pattern in the surface. The function of the next grit is to cut away those scratches and replace them with finer ones. If you jump from P80 to P220, you are trying to use P220 particles to remove P80-depth scratches — they are not large enough to do it efficiently, and you will spend more time sanding than if you had followed the sequence.

The real cost is invisible until finishing. P80 scratches left in a surface that has been sanded to P220 will be visible once stain or clear coat is applied. Stain fills and darkens the scratches, making them appear as dark streaks or lines. Clear coat amplifies the scratch texture by adding reflective depth above it.

The rule: When moving up the grit sequence, move one step at a time. Each grade should fully remove the previous grade's scratches before you progress. Check by sanding one direction at each grade, then sanding the next grade at 90° — when the previous scratches are gone, you can progress.

You can skip grits when moving down (using a finer grit partway through the sequence to start a new job), but never when moving up toward a finished surface.

Frequently asked questions about sandpaper

What do the grit numbers on sandpaper mean?

The grit number represents the particle size of the abrasive — specifically, the mesh size used to sieve and grade the abrasive particles. Higher numbers mean smaller particles (finer abrasive, smoother finish); lower numbers mean larger particles (coarser abrasive, faster material removal). P40 is coarse and aggressive; P2000 is ultra-fine for polishing clear coat.

What is the difference between CAMI and P-grade grit systems?

CAMI is the North American grading standard; P-grade (FEPA) is the international standard used in Australia. At coarse grits (P40–P180), the two systems produce nearly identical particle sizes. At fine grits, they diverge significantly — CAMI 400 is equivalent to approximately P800, meaning a CAMI 400 product is far finer than a P400 product. Most sandpaper sold in Australia is P-grade. P-grade products will have the "P" prefix before the number on the label.

What grit sandpaper should I use on bare wood before painting?

For bare timber before painting, finish at P180–P220. A typical sequence for rough timber is P80 → P120 → P180 → P220. For pre-surfaced or planed timber, starting at P120 is sufficient. Do not finish coarser than P180 for painted surfaces — coarser scratches may show through paint, particularly with water-based products. Sand with the grain on the final pass.

What grit sandpaper should I use between coats of paint?

P320–P400 for between-coat keying on most interior and exterior paints and varnishes. For automotive between-coat sanding (base coat keying): P400–P600 dry or P600–P800 wet. The goal is deglossing and levelling minor imperfections, not material removal — use a light touch and a sanding block on flat surfaces.

What is wet and dry sandpaper used for?

Wet and dry sandpaper (silicon carbide on waterproof film or paper backing) is used wherever water as a lubricant benefits the process: automotive clear coat and lacquer wet sanding (P1000–P3000), glass edge polishing, ceramics, and non-ferrous metals. Water keeps the abrasive cool, prevents loading, and floats away swarf. Standard aluminium oxide paper on paper backing cannot be used wet — it absorbs water and disintegrates.

What is the difference between aluminium oxide and silicon carbide sandpaper?

Aluminium oxide is tougher and longer-lasting — the standard choice for timber, mild steel, and general use. It self-fractures under load, exposing new cutting edges. Silicon carbide is harder and sharper but more brittle — the correct choice for wet sanding, glass, ceramics, hard plastics, and non-ferrous metals. Silicon carbide cuts more aggressively on hard smooth surfaces but wears faster on abrasive or fibrous materials like timber.

Can I use the same sandpaper on both wood and metal?

The same abrasive type (aluminium oxide) works on both timber and metal. The concern is cross-contamination: metal particles embedded in sandpaper used on timber can leave dark staining in timber grain; iron particles transferred from sandpaper used on mild steel will contaminate stainless steel and cause rust staining. Keep separate sandpaper for ferrous metals and non-ferrous materials / timber, clearly labelled.

What grit sandpaper do I need for automotive clear coat wet sanding?

For correcting orange peel in clear coat: P1200–P1500 (wet) to flatten, P2000 (wet) to refine, P2500–P3000 (wet) before machine polishing. Use silicon carbide on film or waterproof backing — standard paper disintegrates wet. For levelling paint runs: start at P800–P1000, progress through P1500 → P2000 before polishing. Check progress under directional light at each stage before moving to a finer grade.

What does hook-and-loop mean on sanding discs?

Hook-and-loop attachment is a Velcro-style system: the sander pad has small hooks; the sanding disc has a loop (soft) backing that attaches to the hooks. Discs can be attached, removed, and replaced quickly without tools. Hook-and-loop is the dominant disc attachment system in Australia for random orbital and detail sanders. The disc diameter must match the sander pad exactly — 115mm, 125mm, and 150mm are the common sizes in the AU market.

Why shouldn't I skip grits when sanding?

Each grit removes the scratches left by the previous grit. If you skip from P80 to P220, you are asking fine particles to remove deep scratches — they are too small to do it efficiently, and the scratches remain. Under stain, oil, or clear coat, those scratches become visible as streaks, dark lines, or a rough texture in the finish. Work through the grades in sequence. At each stage, the surface should show only the scratch pattern of the current grade before you progress.

What grit sandpaper should I use on plaster before painting?

P120 to level joins, fill, tool marks, and surface imperfections. P180–P220 for the final pass before priming. On plasterboard specifically, avoid cutting through the paper facing — sand with moderate pressure and check frequently. For wet-applied plaster and render, P80 can be used to address significant imperfections before progressing to P120. Apply primer before topcoat — bare plaster and render are highly porous and will produce an uneven topcoat finish without it.

What is garnet sandpaper used for?

Garnet is a natural abrasive mineral — soft, orange-red, and not long-lasting compared to aluminium oxide or silicon carbide. It is used primarily for final hand-sanding on bare timber (furniture, joinery, cabinetry) where an exceptionally smooth surface is the goal before staining or oiling. Garnet fractures to leave a smooth cut, and produces less raised grain on bare timber than aluminium oxide. It is not suited to power sanding (wears too quickly) or to metal (not hard enough). Bunnings stocks garnet paper in the fine grades (P120–P220); specialist woodworking suppliers carry finer grades.

What do the P numbers mean on sandpaper in Australia?

The P prefix indicates FEPA P-grade — the international coated abrasive grading standard used throughout Australia and Europe. P stands for Papier (German for paper), reflecting the standard's European origin. FEPA P-grades are defined by ISO 6344, which specifies exact sieve sizes and particle distribution for each grade from P12 through P5000. If sandpaper labelled with a P number appears alongside products without a P prefix, the non-P product is likely CAMI-graded (North American standard) — which uses the same numbers but produces significantly different particle sizes at fine grades. In Australia, P-grade is the default.

Sandpaper and abrasives from AIMS Industrial

AIMS Industrial supplies a full range of abrasives for trade and industrial use: aluminium oxide and silicon carbide sheets, rolls, belts, and hook-and-loop sanding discs in the full grit range from P40 through P3000. Brands stocked include Klingspor, Norton, and Pferd.

Browse our ranges:

Related guides:

Flap Disc & Abrasive Sanding Guide — abrasive minerals for angle grinder discs and fibre discs
Sanding Disc Guide — hook-and-loop disc selection, grit progression for timber and metal
Angle Grinder Guide — disc types, arbor sizes, safe speed selection
Belt Sander Guide — belt sizes, grit selection for portable and stationary belt sanders
Bench Grinder Guide — wheel types, dressing, and safe setup

Contact AIMS for volume pricing on industrial abrasive supplies or to discuss the right product for your application.