Which Floor Sanding Abrasive Should I Choose?

Choosing the right floor sanding abrasive is not simply a matter of selecting a coarse, medium or fine grit. The condition of the floor, existing coating, timber construction, sanding machine, abrasive mineral and backing all affect how efficiently the floor can be sanded and how smooth it will be before finishing.

Starting too fine may waste abrasives and time if the existing coating is particularly resistant. Starting too coarse can unnecessarily remove timber, create deep scratches and make the remaining sanding stages considerably more difficult.

This guide explains how to choose between the professional sanding belts, discs, screens, detail abrasives and specialist Bona systems stocked by Wiltshire Wood Flooring Supplies. Its main focus is timber floor sanding, although several of the heavy-duty SAIT abrasives also have useful applications in joinery, decorating, metal preparation and general workshop sanding.

Start with the Finest Grit That Might Work

One of the most common sanding mistakes is automatically starting every floor with an extremely coarse abrasive.

A better approach is to test a small area using the finest grit you believe may remove the existing coating or correct the surface. If it cuts effectively, continue with that grit. If it struggles, loads immediately or fails to flatten the floor, step back to the next coarser grit and test again.

This approach offers several advantages:

• Preserves more of the timber.
• Reduces the risk of damaging an engineered wear layer.
• Creates shallower initial scratches.
• May remove an entire sanding stage.
• Reduces machine time and abrasive consumption.
• Makes the final scratch-refinement process easier.

This does not mean that coarse abrasives should be avoided. A heavily painted pine floor, uneven boards, thick bitumen contamination or an exceptionally hard factory coating may genuinely require a very coarse starting grit. The important point is to assess rather than assume.

Understanding Floor Sanding Grits

The grit number describes the approximate size of the abrasive particles. A lower number is coarser and removes material more aggressively. A higher number produces a finer scratch pattern.

Do Not Skip Too Many Grits

Each sanding stage is intended to remove the scratch pattern created by the stage before it.

Moving directly from a very coarse abrasive to a fine one may make the floor feel smoother, but the deep scratches can remain beneath the surface. These scratches often become much more visible when stain, oil or lacquer is applied.

As a general principle, avoid excessively large grit jumps. A suitable progression might move from P24 or P40 into P60, then P80 and finally P100 or P120 where required.

The exact sequence depends on the floor, machine and finish. It is not necessary to use every available grit if the previous scratches have already been removed successfully.

Choosing the Correct Abrasive Mineral

Zirconia Abrasives

Zirconia is a hard-wearing abrasive designed to maintain a strong cutting action during demanding work. The grain continually exposes new cutting edges as it wears, helping it remain effective longer than many conventional abrasives.

Within the WWFS range, zirconia is principally used for heavy-duty sanding belts and selected orbital or edging discs.

When should I choose zirconia?

• Removing old floor coatings.
• Flattening uneven solid timber boards.
• Sanding dense hardwood.
• Initial and intermediate belt sanding.
• Working on painted or heavily finished surfaces.
• When abrasive life and sustained cutting speed matter.

Silicon Carbide Abrasives

Silicon carbide has a particularly sharp cutting edge. As the grain fractures, fresh edges are exposed, allowing it to maintain a clean and consistent cutting action.

It is widely used within the WWFS disc and screen range for floor edging, rotary sanding, multidisc finishing and surface preparation.

When should I choose silicon carbide?

• Progressive sanding of timber floors.
• Final sanding before stains, oils and lacquer systems.
• Edging with compatible floor sanding machines.
• Rotary or multidisc floor sanding.
• Sanding cured coatings where a sharp abrasive is useful.
• Intercoat abrasion with suitable screens.

Aluminium Oxide Abrasives

Aluminium oxide is a dependable general-purpose abrasive. It combines good durability with a controlled cut and is suitable for a wider range of workshop and preparation tasks than a flooring-specific abrasive alone.

It is particularly useful for orbital sanding and detailed work on timber, paint, fillers, plaster and compatible metal surfaces.

Bona 8300 Abrasives

Bona 8300 abrasives are premium professional products developed specifically for timber floor sanding.

Their engineered abrasive grain offers fast cutting, reduced fibre ripping and long working life. Antistatic properties help limit clogging and improve dust extraction.

Bona Diamond Abrasives

Bona Diamond Abrasive Discs are specialist hook-and-loop abrasives available in P80, P120 and P240.

They are intended for use with the Bona Quattro Disc and the correct pressure-equalising intermediate pads. They should not be fitted directly to the Quattro Disc.

Recommended applications

• Controlled fine sanding of bare timber.
• Preparing timber before stains and coloured oils.
• Abrading compatible existing lacquer before recoating.
• Preparing hard factory finishes.
• UV-cured and ceramic-reinforced coatings.
• Commercial deep-clean and overcoat systems.

Sanding Screens and Mesh Abrasives

Sanding screens are open mesh abrasives designed to allow dust to pass through the screen rather than collecting beneath a conventional solid disc.

Both sides are abrasive, allowing the screen to be turned over during use. Their open construction also helps reduce clogging.

The WWFS range includes:

• SAIT 407mm Nylon Mesh Sanding Screens.
• Bona 407mm Sanding Screens.

Suitable uses

• Removing raised grain after a compatible primer or seal coat.
• Lightly keying suitable existing lacquer before recoating.
• Smoothing a timber surface during the final preparation stages.
• Controlled intercoat abrasion where required by the finish manufacturer.
• Blending minor sanding inconsistencies.

Which Abrasive Fits Which Machine?

Choosing a Starting Grit

These are starting points for assessment, not fixed specifications. Machine power, timber hardness, board flatness and coating type all affect the result.

Example Floor Sanding Sequences

The sequences below demonstrate the principle of progressive scratch refinement. They should be adjusted after testing the actual floor.

Belt Sander, Edger and Multidisc Workflow

Sanding Engineered Wood Flooring

Engineered flooring has a real timber wear layer above its core. The floor may be sandable, but the available amount of timber is limited.

Before sanding:

• Confirm the original wear-layer thickness.
• Assess whether the floor has been sanded before.
• Allow for the depth of bevels, damage and board variation.
• Check for visible plywood or core material around deep scratches.
• Begin with the finest grit likely to complete the work.

Sanding Parquet Flooring

Parquet blocks contain grain running in multiple directions. A belt or edger will therefore be sanding with the grain on some blocks, across the grain on others and diagonally across many more.

Use controlled passes and avoid leaving an aggressive belt pattern as the final visible sanding stage. A suitable multidisc or orbital finishing process helps blend directional scratches across the pattern.

Herringbone, basket weave, mosaic and Versailles-style panels may each require a slightly different approach according to their layout and condition.

Old Paint, Bitumen and Heavy Coatings

Thick paint and old adhesive contamination can clog an abrasive before it has had the opportunity to cut the timber.

Begin with a controlled test. If a medium-coarse abrasive cuts successfully, there is no advantage in moving immediately to P24. Where the coating is thick, sticky or the boards require flattening, a coarse zirconia belt may be necessary.

Inspect frequently for nails, screws and other metal fixings. These can damage the abrasive, create sparks and mark the sanding drum.

Other Uses for WWFS Heavy-Duty Abrasives

Floor sanding remains the principal purpose of the WWFS abrasive range, but several products are suitable for other professional applications when used with compatible machinery.

Why Abrasives Clog

Abrasives can load or clog because of:

• Soft or heat-sensitive coatings.
• Wax, polish or oil contamination.
• Insufficient dust extraction.
• Excessive machine pressure.
• Heat build-up.
• Sanding before filler or coating has fully cured.
• Using an abrasive construction unsuited to the material.

Once the abrasive surface is fully loaded, pressing harder rarely restores the cut. Excess pressure creates more heat, increasing the likelihood of further clogging and visible sanding marks.

When Should an Abrasive Be Changed?

Replace an abrasive when:

• The cutting rate has reduced noticeably.
• The belt or disc is heavily clogged.
• The scratch pattern has become inconsistent.
• The backing is damaged, torn or distorted.
• The belt joint shows signs of failure.
• The hook-and-loop attachment no longer holds securely.
• Excess heat is developing despite correct machine use.

A worn abrasive may still look usable but can polish the surface rather than cut it evenly. This wastes time and may change how the timber accepts the finishing product.

Common Floor Sanding Mistakes

Starting too coarse

This removes unnecessary timber and creates scratches that require several later stages to eliminate.

Starting too fine and refusing to adjust

If the finish is not being removed efficiently, move one grit coarser instead of using large quantities of unsuitable fine abrasive.

Skipping the intermediate stage

A fine abrasive may smooth the ridges around a deep coarse scratch without removing the bottom of the scratch itself.

Using different final grits on the edges and centre

This can create visible colour and absorption differences after staining, oiling or applying a pigmented primer.

Forcing the sanding machine

Excess pressure increases heat and loading. Allow the machine weight, abrasive and correct walking speed to perform the work.

Using the wrong disc size or extraction pattern

Poor fit can affect dust extraction, balance and abrasive retention.

Failing to inspect between grits

Once the next grit has been used, it becomes harder to identify whether a scratch came from the current stage or an earlier one.

Finishing too finely

Excessively polished timber may accept stains, pigmented oils and primers unevenly or too weakly.

WWFS Abrasive Range

Frequently Asked Questions

Our Final Recommendation

Abrasive suitability, grit sequence and final sanding grit depend on the floor construction, coating, timber species, machine and intended finish. Always confirm machine dimensions and attachment systems before ordering. Follow the sanding-machine, abrasive and finishing-product manufacturer instructions, use effective dust extraction and wear appropriate personal protective equipment.