Which sandpaper abrasive should I use on wood?

Aluminum oxide is the all-purpose choice for most woodworking—durable and self-renewing. Garnet cuts smoothly and leaves a fine finish but wears faster—great for hand-sanding between coats. Silicon carbide excels for wet sanding, finishes, plastics, and between coats due to its sharp, brittle cut. Ceramic/alumina zirconia is extremely aggressive and long-lasting for heavy stock removal and leveling.

How do I choose the right grit progression?

Start coarse enough to remove defects, then step through logical jumps (~40–60% increases): e.g., 80→120→150→180→220 for most hardwoods. Skipping steps leaves deep scratches; too many steps wastes time. For stain-grade surfaces, stop at 180–220; for film finishes that will be leveled, 220–320 is common.

What’s the difference between CAMI and FEPA (P-grit) numbers?

CAMI (U.S.) and FEPA P-grits (Europe) are similar but not identical. P-grits generally run slightly finer than the same CAMI number at higher grits. When switching brands/systems, consult a conversion chart or pick the nearest listed micron size to keep your scratch pattern consistent.

How do I prevent swirl marks with a random-orbit sander?

Use quality hook-and-loop discs that match the pad’s hole pattern, keep the pad flat, apply only light pressure, and let the sander’s weight do the work. Vacuum extraction reduces loading. Wipe or blow off dust between grits and finish with a light hand-sand in the grain direction to knock down residual swirls.

Why does my sandpaper clog (load) so fast?

Resins, pitch, and finish dust can gum up the abrasive. Use open-coat papers for softwoods, pair with dust extraction, and clean discs with a rubber abrasive cleaner. If sanding finishes, switch to stearated (non-loading) papers or silicon carbide and avoid excessive heat from heavy pressure.

When should I replace a sanding disc or sheet?

If cutting slows noticeably, the surface looks burnished, or you must press harder, it’s time to swap. Dull paper creates heat, swirls, and uneven scratch patterns—costing more time in later steps than a fresh sheet would.

Is wet sanding useful on wood?

Wet sanding with silicon carbide can level cured film finishes (varnish, lacquer) or create a slurry with oil finishes for pore-filling. Avoid wet sanding raw wood with water—grain can raise. If you need grain-raise control, pre-raise with a damp wipe, dry, then make a light pass at the final grit.

Sandpaper: What Is It and What Is It Used For?

Sandpaper is a flexible sheet of abrasive material used to smooth, shape, clean, or polish a surface by abrasion. It consists of a backing (usually paper, cloth, or film) coated with hard mineral grains such as aluminum oxide, silicon carbide, garnet, or ceramic. These abrasive particles are bonded to the backing with resin or glue, creating a cutting surface that shaves away tiny amounts of wood, metal, plastic, glass, or painted finishes.

Sandpaper is indispensable in woodworking, metalworking, automotive refinishing, construction, and DIY repair. Woodworkers use it to flatten boards, break sharp edges, and prepare hardwoods like oak, maple, or black walnut for stain and varnish. Metalworkers rely on sandpaper to knock down welds, remove rust, and prepare steel or aluminum for primer. In the automotive trades, sanding discs and sheets are used on body filler, primer, and clear coat to achieve a flat, high-gloss finish. Around the home, sandpaper is equally useful for smoothing drywall joints, cleaning up paint drips, or easing sharp edges on plastic and other materials.

Sandpaper is sold in many grit sizes (the coarseness of the abrasive), formats (sheets, rolls, belts, discs, and sponge blocks), and materials. Choosing the right grit and abrasive type is the key to fast, clean, and efficient sanding.

Sandpaper Grit Numbers and What They Mean

The grit number describes the size of the abrasive particles. Lower grit numbers mean larger particles and more aggressive cutting; higher numbers mean smaller particles and a smoother finish. Common sandpaper for wood, metal, and automotive work ranges from about 40 to 3000 grit.

Coarse Grit Sandpaper (40–80 grit)

Coarse grits remove material quickly and aggressively. They are best for:

Stripping thick paint, varnish, or old finish from wood or metal
Leveling badly cupped or twisted boards before finer sanding
Shaping edges and rounding corners
Removing heavy rust or scale

Coarse sandpaper leaves visible scratch marks and is not suitable for final finishing. Always follow with progressively finer grits.

Medium Grit Sandpaper (100–150 grit)

Medium grits are the workhorse for most general-purpose sanding:

Removing light scratches and planer marks from solid wood
Preparing bare wood surfaces for stain or primer
Shaping and smoothing hardwoods such as oak, maple, or teak
Sanding plastics and composites without gouging

Medium grit strikes a balance between material removal and surface refinement, making it ideal as a starting point for many woodworking and remodeling projects.

Fine Grit Sandpaper (180–240 grit)

Fine grits are used when you are approaching the finishing stages:

Smoothing the grain of softwoods like white pine or spruce
Final passes on hardwoods before stain or clear coat
Knocking down raised grain after a damp cloth wipe
Sanding between primer or sealer coats

Fine sandpaper produces a smooth, even surface that is ready for most paints, stains, or clear finishes.

Very Fine Grit Sandpaper (320–400 grit)

Very fine grits push into the polishing and ultra-smooth preparation range:

Sanding between finish coats (varnish, lacquer, urethane)
Refining previously sanded furniture surfaces for a “hand-rubbed” look
Automotive primer smoothing prior to basecoat

When used lightly, very fine paper helps level dust nibs and minor imperfections without cutting through the finish.

Extra Fine Grit Sandpaper (600–800 grit)

Extra fine grits are used where an ultra-smooth surface is needed:

Final leveling of clear finishes on fine furniture or instruments
Polishing metals before buffing compounds
Delicate work on veneers or thin finishes where aggressive sanding could cut through

Super Fine Grit Sandpaper (1000–1500 grit)

Super fine grits are common in the automotive and polishing trades:

Flattening and polishing clear coats before buffing
Blending touch-up areas into existing finishes
Refining plastics and acrylics to near-gloss clarity

Ultra-Fine Grit Sandpaper (2000–3000 grit)

Ultra-fine grits are used for the most delicate and precise work:

Final wet sanding of automotive clear for show-quality gloss
Polishing metals and plastics before compounds and buffing wheels
Removing minor swirl marks or haze from previously sanded surfaces

At this level, sandpaper behaves more like a polishing cloth than a cutting tool.

Sandpaper Abrasive Materials: Aluminum Oxide, Silicon Carbide, Garnet, Ceramic

Different abrasives excel on different materials. Choosing the right grain type improves cutting speed, surface quality, and sandpaper life.

Aluminum Oxide Sandpaper

Aluminum oxide is the most common abrasive used in sandpaper. It is tough, long-lasting, and fractures in use to expose fresh cutting edges. Aluminum oxide is ideal for:

General-purpose woodworking on both softwoods and hardwoods
Sanding metals and metal primers
Shaping and smoothing plastics and composites

For most shop or jobsite tasks, aluminum oxide is the default “go-to” sandpaper.

Silicon Carbide Sandpaper

Silicon carbide is extremely hard and sharp. It cuts aggressively and leaves a very fine scratch pattern, especially when used wet. Common uses include:

Sanding stone, glass, ceramic tile, and concrete edges
Refinishing automotive paint and clear coat (often as wet-or-dry paper)
Working on non-ferrous metals such as aluminum, brass, or copper

Silicon carbide sandpaper is an excellent choice whenever you need fast cutting on hard or brittle surfaces.

Garnet Sandpaper

Garnet is a natural abrasive favored by many traditional woodworkers:

Excellent for hand sanding bare wood, especially softer species
Leaves a smooth scratch pattern that finishes well
Less likely to clog quickly when sanding resinous woods

Garnet wears faster than synthetic abrasives but produces a very clean, “friendly” cut on wood.

Ceramic Sandpaper

Ceramic abrasives are premium, high-performance grains used where maximum cutting power and longevity are required:

Heavy stock removal on hardwoods and tough materials
Use with power sanders, belts, and discs for long life under high pressure
Ideal for demanding industrial or professional applications

Ceramic sandpaper stays sharp for a long time and is especially effective on dense hardwoods like rosewood, mahogany, and teak.

Sandpaper Backing Materials: Paper, Cloth, and Film

The backing material supports the abrasive and determines how flexible, durable, and tear-resistant the sandpaper is.

Paper-Backed Sandpaper

Paper-backed sandpaper is the most common type:

Flexible and lightweight
Ideal for hand sanding blocks and general-purpose work
Available in many grits and often sold as sheets or rolls

Paper-backed abrasives are cost-effective and perfect for most woodworking and drywall sanding tasks.

Cloth-Backed Sandpaper

Cloth-backed sandpaper uses a woven fabric backing, making it:

More durable and tear-resistant than paper
Suitable for belt sanders, drum sanders, and high-friction applications
Better able to withstand repeated flexing and heavy pressure

It is often used for aggressive sanding of metals and hard surfaces where paper would quickly fail.

Film-Backed Sandpaper

Film-backed sandpaper uses a thin polyester film:

Highly resistant to tearing and edge breakdown
Provides very uniform scratch patterns—ideal for fine finishing
Common in automotive finishing and high-end woodworking where a flawless surface is required

Film-backed abrasives excel in precision applications, especially when combined with wet sanding.

Wet or Dry Sandpaper

Many sandpapers can be used either dry or with water or lubricant for wet sanding.

Dry sanding is the default for most wood, drywall, and general-purpose jobs. It is quick and convenient but generates more dust and heat. Vacuum extraction or a dust mask is highly recommended, especially when sanding finishes or joint compound.

Wet sanding uses water (or sometimes a dedicated lubricant) to:

Reduce heat and friction
Minimize airborne dust
Keep the abrasive from clogging with removed material

Wet-or-dry silicon carbide sheets are commonly used for:

Automotive primer, basecoat, and clear coat smoothing
Polishing metal and plastic parts
Fine finishing on high-gloss surfaces

Open Coat vs Closed Coat Sandpaper

Sandpaper is also classified by how densely the abrasive grains are packed on the backing:

Open Coat Sandpaper

Open coat sandpaper has abrasive grains spaced farther apart, with more open area between them:

Less likely to clog with dust, resin, or paint
Ideal for sanding softwoods, painted surfaces, and materials that generate lots of debris
Often used in woodworking and paint removal applications

Closed Coat Sandpaper

Closed coat sandpaper has abrasive grains packed tightly across the entire surface:

More aggressive cutting action per stroke
Better for hard materials where clogging is less of a problem
Common on metalworking abrasives and fine finishing papers

Choosing between open and closed coat sandpaper depends on the material being sanded and whether you prioritize fast cutting, resistance to clogging, or a very uniform scratch pattern.

Sandpaper is an essential tool for achieving smooth and refined surfaces on wood, plastic, metal, glass, and drywall. Understanding grit numbers, abrasive materials, backing types, and coat density makes it easier to select the right product for each stage of your project—from heavy stock removal to the final polishing pass.

Sandpaper

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