Timber coatings: a practical guide for trade and specifiers
What this guide covers
Everything we get asked about timber coatings, in one place: what the different coating families actually are, how curing works and why it decides your programme, what is in the air while a finish dries, how to work out what a job needs, and how to apply and maintain it. Each section links to the guide that goes deeper on it.
Most coating decisions get made on price per litre and a photograph of a finished floor. Neither tells you much. What actually determines whether a job runs well is how the finish cures, what it puts into the air while it does, and how far it goes.
The coating families
Most timber finishes fall into two camps. Film finishes, meaning lacquers and varnishes, sit on top of the timber as a layer. Penetrating finishes, meaning oils and hardwax oils, soak into the timber and leave a thin protective layer rather than a skin.
The practical difference shows up when something gets damaged. A film finish breaks, and the break has edges, so repairs usually mean taking the whole area back. A penetrating finish wears thin rather than breaking, which is why an oiled floor can be cleaned, re-oiled and blended without stripping it.
Then there are the terms that describe where and how a finish was cured rather than what it is made of, which is where most of the confusion lives. UV oiled means a hardwax oil cured under lamps in a factory before the boards were delivered. LED cured means a coating that hardens under light on site, as it is applied.
How curing works, and why it sets your programme
A conventional oil hardens by reacting with oxygen in the air. That takes hours to become touch dry and days to harden properly, and it slows down further when it is cold or humid. A conventional lacquer hardens as its solvent evaporates, which has the same consequence: time.
Energy curing works differently. A specific wavelength of light, 395nm in our case, triggers the coating to cross-link on contact. The film is fully hard as the lamp passes over it, not touch dry. Nothing has to evaporate and nothing has to react with the air.
That one difference removes the waiting, and the waiting is where most of the real cost sits: racks occupied, floor space tied up, a room that cannot be used, a handover date that slips because the finish was not ready rather than because the work was not done.
What is in the air while it dries
Solvents are in traditional coatings for a reason. They thin the finish and speed up drying. The same property that makes them useful, their eagerness to evaporate, is what puts them into the air of the room you are standing in.
Those compounds are called VOCs, volatile organic compounds, and they do not stop being released the moment a surface feels dry. Many keep off-gassing for days, and in some cases months, while the film slowly finishes curing underneath. The lingering workshop smell is that process still running.
This matters most where a space is occupied: a school, a ward, an office, a home that someone is still living in. A coating that cures under light rather than by evaporation has no solvent to release, which changes what is possible on an occupied site.
Working out what a job needs
Hardwax oil is sold by the litre and used by the square metre, which is why the price on the tin tells you very little on its own. A tin at half the price with half the coverage costs you the same, and a tin at half the price with a third of the coverage costs you more.
Most hardwax oils cover 20 to 30 square metres per litre, and most data sheets quote that figure per coat while specifying two coats. Multiply it out before comparing anything.
| Step | What to do |
|---|---|
| 1 | Measure the area in square metres |
| 2 | Divide by the coverage per litre from the data sheet |
| 3 | Multiply by the number of coats |
| 4 | Add about 10 per cent for waste and edges |
Applying it
The method differs between a floor and a workbench, mostly in the equipment and in how the oil is worked into the surface. Both follow the same principle: prepare evenly, apply sparingly, work it in, take the excess off, then cure.
Over-application causes more finish failures than everything else combined. Hardwax oil is meant to penetrate, and anything the timber cannot absorb sits on the surface with nothing to react with.
- Flooring application guideSanding through the grits, cutting in, buffing, and curing a floor that takes foot traffic the same day.
- Furniture and joinery guideThe bench scale method, from 120 grit through to a 320 grit finish, with curing between coats.
Specifying for a live building
If you are writing a finish into a schedule, the clause that matters most is often missing from it. State the maximum time the area may be out of use, not just the product. That is the real requirement, and it is the one that decides whether the job is deliverable in a half term or a weekend.
Ask for the VOC content from the technical data sheet rather than accepting a description on a tin, because water based does not mean solvent free. Set a reoccupation condition in plain terms. And ask how the finish is repaired, because over a building's life that matters more than how it looks on day one.
We also run a free hands on hour at practices anywhere in the UK, where everyone coats and cures their own oak samples. It is the fastest way to understand the difference, and people keep the boards.
Seeing it in use
Retail, hospitality and residential projects finished with Oslek LED Hardwax Oil, including European oak herringbone, custom colour matched floors and heritage interiors. The projects below are Australian, where the system has been in use longest.
- Camilla and Marc, ArmadaleEuropean oak herringbone in a heritage terrace boutique, finished in a custom grey oil. Winner of an Australian Interior Design Award.
- Camilla and Marc, BondiCustom stained oak herringbone running alongside terrazzo tiling in a flagship store.
- The Panel HouseEuropean oak flooring in a 950 square metre certified Passivhaus Premium home, chosen for indoor air quality.
- Aesop, DoncasterCork wall panels finished in LED Hardwax Oil Clear and cured in place on site.
- Rifle RangeTimber wall panelling and ceiling features in a passive house retrofit.
- NewNewA modular pavilion built on circular design principles, finished so the timber can be refinished and reused.
- Stay StoolA reissued Tom Skeehan design, finished for everyday use on a timber and steel frame.
Common questions
What is the difference between hardwax oil and lacquer?
A lacquer forms a film on top of the timber. A hardwax oil penetrates it and leaves a thin protective layer. The practical consequence is repairability: a lacquer breaks and usually needs taking back, while an oiled surface wears thin and can be cleaned, re-oiled and blended.
How long before a newly finished floor can be used?
It depends entirely on the coating. A conventional hardwax oil is typically touch dry in hours and fully cured in days. An LED cured coating is walkable as soon as the lamp has passed over it.
Can timber be refinished in an occupied building?
Yes, with the right finish and sensible phasing. The limiting factors are odour and drying time rather than the sanding itself. A solvent free finish that cures on contact can be handed back the same day.
Does a more expensive coating cost more per square metre?
Not necessarily, and often the opposite. Price per litre only means something once you divide it by coverage and multiply by the number of coats the data sheet specifies.
Try it before you commit
Most people start with a sample. Coat a piece of timber, cure it under the lamp, and see in seconds what the rest of this guide describes. Then order the full size when you are ready.
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