Buffing between coats: why the "boring" step saves the finish
A floor finish is only as durable as its weakest inter-coat bond. When one coat cures too hard before the next arrives, or when dust, lint and fibres land on a tacky coat, the resulting floor might look fine on handover and peel in sheets three years later.
Inter-coat abrasion, usually called buffing, is how professional finishers prevent this. The ATFA Code of Practice for Coating of Timber Floors prescribes mesh or screen abrasion between every coat on every system, and for good reason.
What buffing actually does
Two mechanical functions:
- Mechanical key. A micro-abraded surface gives the next coat something to physically grip. Without it, coat 2 sits on top of a glassy coat 1 and relies entirely on chemical bonding, which is weaker and less forgiving.
- Dust nib removal. Every cured coat has dust nibs, fibres from the roller, and tiny bubbles that have popped. Buffing takes these down to below the plane of the next coat, which buries them invisibly.
Skip the buff and your final coat is only as smooth as the roughest dust nib in the previous coat.
Mesh versus screen versus pad
Three common abrasion media, each with different use cases:
Abrasive mesh (120, 150, 180 grit)
Fibreglass backing with aluminium oxide or silicon carbide particles bonded to both sides. Flexible, does not clog quickly, used on a weighted buffer or pole sander. Preferred for water-based finishes and the lightest touch. EcoGrit stocks sia mesh in common grits.
Abrasive screen (80, 100, 120 grit)
Stiffer grid, more aggressive cut. Used for heavier first-coat abrasion or when a previous coat cured too hard to mesh effectively.
Maroon / brown pads (very fine)
Non-woven synthetic pads, no grit bonded - act as a conditioner, knocking down nibs without significantly texturing the film. Useful for a final inter-coat pass on gloss systems where minimal texture change is wanted.
Grit selection by system
| System | Between primer and coat 1 | Between coat 1 and coat 2 |
|---|---|---|
| Berger AquaSeal 2K PU | 120 mesh | 150-180 mesh |
| Loba Invisible Protect | 120 mesh | 180 mesh |
| Bona Traffic HD | 120 mesh | 150 mesh |
| Oil-based polyurethane | 120 screen | 120 mesh |
| Rubio OP2C | Not required (single coat) | N/A |
| WOCA Master Oil | Not required | N/A |
Hard wax oils like Rubio and WOCA Master Oil are single-coat systems by design. No inter-coat abrasion step is needed (and none is possible - the cured oil is in the timber, not on it).
Timing is everything
Buff too early and the film is still soft; the mesh will gum up and leave rubbery lines. Buff too late and the film is fully cured; no amount of 150 grit will key the surface, leaving you to sand back aggressively.
The window varies by system and ambient conditions. As a general rule:
- Water-based: buff 2-4 hours after application at 20 C / 50% RH
- Oil-based polyurethane: buff 12-16 hours after application
- Hybrid oil-modified water-based: per manufacturer TDS, typically 6-8 hours
If the coat still feels tacky to the touch, it is too early. If you cannot dent it with a fingernail pressed firmly, it may be too late.
Equipment: weighted buffer is the gold standard
A 12-inch weighted floor buffer running at 175 rpm is the professional tool for inter-coat abrasion. The weight is what does the work, the rpm keeps the abrasive fresh, and the head size bridges small cups and inconsistencies without following them.
At the DIY level, a square pole sander with a mesh pad works for residential areas but is slower and more tiring than a rented buffer. A random-orbit sander is a poor substitute - orbit marks telegraph through the next coat.
Do not use a drum sander or belt sander for inter-coat work. Way too aggressive; you will cut through into the timber and leave drum marks under the final coat.
Procedure
- Verify the previous coat is dry enough (fingernail dent test, or follow TDS cure window)
- Fit fresh mesh or screen to the buffer pad
- Buff with the grain first, overlapping by 50%
- Second pass across the grain if the surface still shows gloss spots (not fully abraded)
- Edges: use a random-orbital sander with mesh or hand-abrade with a cork block
- Check against a low-angle light: any glossy spots are un-abraded and will cause adhesion failure. Re-buff those spots before proceeding
- Vacuum thoroughly: between coats, a HEPA-filtered vacuum is non-negotiable. Then tack-rag with a lint-free cloth dampened (water-based) or with a compatible thinner (oil-based)
- Recoat within 4 hours of buffing. Longer and surface contaminants will settle back on
Common mistakes
- Skipping the buff entirely. "Next-coat-within-the-window" ready systems still need it for dust nib removal.
- Using too-fine a mesh for a too-hard coat. 150 mesh cannot key a fully-cured oil-based polyurethane. Step down to 120 screen.
- Over-buffing. Spending 20 minutes per m² with 120 mesh will cut through the coat. 1-2 minutes per m² is plenty.
- Not vacuuming between buff and recoat. The whole point of buffing is removing dust - leaving it on the floor wastes the work.
- Buffing in high humidity. Water-based coats absorb humidity during buffing, extending the next cure window. Run a dehumidifier during coating days.
Our trade advice
Run a weighted buffer with 150 mesh between every water-based coat. Change mesh every 30-40 m² of floor. HEPA-vacuum and tack-rag between buff and coat. Never skip the step, regardless of how well the previous coat appears to have gone down.
For Berger AquaSeal, Loba or Bona inter-coat mesh by the case: +61 401 270 818 or email sales@ecogrit.com.au. We stock sia screens and mesh in all common sizes.