Recycled Hardwood Flooring

Sanding, priming, and finishing guide for recycled hardwood floors -- a mix of reclaimed Australian species with variable hardness, hidden hazards, and unique character that requires careful preparation and a tannin-control primer.

Species characteristics

• Janka hardness: Variable -- a recycled hardwood floor may contain boards from multiple species ranging from 5 kN (softer species) to 14+ kN (ironbark). The inconsistency in hardness is the primary sanding challenge.
• Grain: Mixed. Expect straight grain, interlocked grain, and everything in between across different boards. Some boards will sand cleanly while adjacent boards tear.
• Colour: Wide variation. Recycled hardwood floors are prized for their character -- the mix of pale, dark, warm, and cool tones across boards is the visual appeal. Each board has its own history and patina.
• Tannin level: Assume high. Older Australian hardwoods -- especially those sourced from demolished buildings, bridges, and wharves -- carry concentrated tannins from decades of seasoning. Even species that would be low-tannin in new timber can present tannin risk in recycled form.
• Common issues: Hidden nails, staples, and screws that destroy sanding belts. Old paint, varnish, and tar residue. Variable hardness causing uneven sanding. Tannin bleed from concentrated tannins in aged timber. Board-to-board height variation from mixed sources.

Pre-sanding inspection

This step is critical on recycled hardwood and should not be skipped:

• Walk the entire floor with a strong torch at a low angle. Look for nail heads, staple legs, screw heads, and any metal above the surface. Punch every nail and staple below the surface with a nail punch. Remove any screws.
• Check for old paint and tar. Some recycled timber carries remnants of old coatings on the face or edges. These coatings clog belts and can contain lead in older timbers. If lead paint is suspected, test before sanding.
• Identify loose or damaged boards. Recycled floors often have boards that have moved since installation. Re-fix any loose boards before sanding. Sanding a loose board creates bounce marks that show through finish.
• Run a metal detector over the floor. Even a cheap handheld metal detector picks up hidden nails and staples that visual inspection misses. One hidden nail can tear a belt in half.

Recommended grit sequence

For a standard recycled hardwood sand:

• Belt sander: P36 → P60 → P80 → P100 (SIA belts). Start at P36 to cut through old patina, residual coatings, and height variation between boards.
• Edger: Match the belt grits. P36 → P60 → P80 → P100.
• Buffer/screen: P120 screen or mesh to blend belt and edger zones.

Budget 2-3x the normal quantity of belts. Hidden fasteners, old coatings, and mixed hardness all accelerate belt wear. Replace belts at the first sign of damage -- running a torn belt creates scratch patterns that take extra grits to remove. For floors with severe height variation, a P24 first cut may be necessary. Use the Grit Sequence Picker to get a sequence tuned to the exact condition.

Recommended primer

Bona Prime Intense -- the safe choice for recycled hardwood under water-based topcoats. The mix of species and the concentrated tannins in aged timber make it impossible to predict tannin behaviour board by board. Prime Intense seals the tannins across all species in the floor.

Do not use a general-purpose primer on recycled hardwood. Even if some boards in the floor are low-tannin species, the high-tannin boards will bleed through a general-purpose primer and ruin the entire finish. Prime Intense handles the worst-case boards while still performing well on the low-tannin ones.

Prime Intense also enhances the natural colour variation in recycled hardwood, deepening the warm tones and giving the floor more visual depth than a neutral primer would.

If finishing with solvent polyurethane (Handley Urethane), tannin bleed is less of a risk because solvent does not activate tannins. A solvent sealer coat is still recommended for adhesion on the variable surface.

Recommended topcoats

• Bona Traffic HD: Commercial-grade 2K water-based. Maximum durability for recycled hardwood floors in high-traffic settings.
• Bona Wave 2K: Heavy residential 2K. Excellent durability and value. A strong choice for residential recycled hardwood where maximum abrasion resistance is needed.
• Bona Mega: Single-component residential. Reliable and easy to apply. Suitable for standard residential traffic on recycled hardwood.
• Bona Traffic GO: Fast-cure 2K for same-day turnaround. Furniture back in 12 hours.

Common mistakes on recycled hardwood

• Skipping the nail inspection. One hidden nail tears a belt and creates a deep gouge in the floor. Walk the entire floor with a torch and a nail punch before the sander touches the surface. Use a metal detector for hidden fasteners.
• Using a general-purpose primer. Recycled hardwood is a mix of species. Assume the worst-case tannin level and use Prime Intense. A callback on a recycled floor means sanding back through all that character and starting over.
• Starting too fine. Recycled hardwood floors typically have old coatings, height variation, and deep patina that require aggressive initial cutting. Start at P36, not P60. The first cut needs to flatten the floor and remove all old material.
• Under-budgeting abrasives. Hidden fasteners, old coatings, and mixed hardness destroy belts faster than new timber. Budget 2-3x the normal belt quantity and bring extra edger discs. Running out of abrasives mid-job is not an option on a floor this variable.
• Ignoring board-to-board height variation. Recycled boards from different sources may sit at slightly different heights. The P36 first cut needs to flatten the floor. If variation is severe, a P24 initial cut or even a pass with a floor plane may be necessary before the grit sequence begins.

FAQs: recycled hardwood flooring

Can recycled hardwood be stained?

It can, but the result is unpredictable. Different species absorb stain at different rates, so the colour will vary across boards. Most clients choose recycled hardwood for its natural character variation and prefer a clear finish that shows the mix of tones.

How do I handle old lead paint on recycled boards?

If the recycled timber is from a pre-1970s source and has visible paint residue, test for lead before sanding. Lead paint dust is a serious health hazard. If lead is confirmed, follow the relevant state guidelines for lead paint removal -- this typically requires containment, HEPA filtration, and licensed disposal.

Is recycled hardwood harder to sand than new timber?

Yes. The combination of aged timber (which is denser than freshly milled timber), hidden fasteners, old coatings, and mixed species makes recycled hardwood the most demanding floor type to sand. Budget extra time and extra abrasives.

Tools

• Grit Sequence Picker -- pre-set for recycled hardwood
• Primer Picker -- confirms Prime Intense for recycled hardwood
• Coverage Calculator -- litres of primer and topcoat for the job