The short answer
Osmo Polyx-Oil and Oslek LED Hardwax Oil are both hardwax oils. The difference is how they harden. Osmo cures in air, which its data sheet puts at 8 to 10 hours to touch dry and two to three weeks to full hardness. Oslek cures under a 395nm LED lamp, in seconds. The surface takes traffic straight away, you see the finished colour there and then, and there is nothing left to off gas. If your problem is the waiting, that is the whole comparison. If your problem is the price of a litre, Osmo is cheaper.
Most people choosing between these two are not really choosing a finish. They are choosing how long a room, a workshop or a staircase is out of use.
The difference, on one scale
Both products below are drawn on the same linear scale, nought to twenty one days.
A finish that is touch dry is not a finish that is finished. In between those two points the floor is walkable but vulnerable. Rugs, heavy furniture and wet cleaning all have to wait.
On a domestic job that is an inconvenience. On a shop, a school or a ward it is the reason the job happens at night, over a holiday, or not at all.
What the waiting actually costs you
Eight to ten hours is not just a number on a data sheet. It is three separate problems, and every one of them costs time or money.
1. You cannot see the colour until it is dry
Hardwax oil goes on darker than it finishes, and the sheen settles as it cures. So the colour you are looking at while the floor is wet is not the colour the client is going to get. With Osmo you find out the next day. If it is wrong, you have lost the day and the material.
Under an LED lamp the coating is cured as the lamp passes over it, so the colour in front of you is the finished colour. You can put a sample down, cure it, and hold it against the joinery while the client is still standing there.
2. A wet floor collects everything in the air
A surface that stays open for eight to ten hours is a surface collecting airborne dust for eight to ten hours. On a building site, in a workshop, anywhere with other trades moving, that is the difference between a clean finish and one that has to be cut back and done again.
A coating that is hard before you have moved the lamp has no window for dust to land in.
3. Two coats means two visits
Osmo specifies two coats on new timber, with the second after the first has dried. On site that is two attendances, or an overnight stay, or a floor left protected and unusable in between. In a workshop it is the same components handled twice and racked in between.
Oslek is one coat, cured as you go. You arrive, you finish, you leave.
Side by side
| Oslek LED Hardwax Oil | Osmo Polyx-Oil Original | |
|---|---|---|
| How it hardens | Under a 395nm LED lamp | In air, by oxidation |
| Touch dry | Immediately | 8 to 10 hours |
| Full cure | Immediately | 2 to 3 weeks |
| Coats on new timber | One | Two |
| Coverage per litre, per coat | 40 to 50 m² by hand, 70 to 80 by machine | Approx. 24 m² |
| VOC content | 6.4 g per litre | Up to 500 g per litre |
| Needs a lamp | Yes | No |
The coverage line is the one most people miss. Osmo quotes approximately 24 square metres per litre and specifies two coats on new timber. Oslek covers 40 to 50 by hand in a single coat. Our coverage and cost guide sets out how to work that through for a real job.
The smell, and what is actually in the tin
Osmo's own data sheet states the product contains a maximum of 500 grams of VOC per litre, at a stated density of 0.88 to 0.95 grams per cubic centimetre. At that maximum, more than half the weight of the tin is solvent that has to evaporate into the room before the finish is finished.
That evaporation is the smell. It is also why the room needs ventilating, why people are asked to stay out, and why the job gets booked for a Friday or a school holiday.
Oslek LED Hardwax Oil contains 6.4 grams of VOC per litre, which is the same figure as 99.4 percent VOC free stated the other way round. It hardens by light rather than by evaporation, so there is almost nothing to give off and no solvent smell to clear. That is the practical reason it suits occupied buildings: a ward, a classroom or a shop floor can be finished and handed back without emptying the space first. We have written about what that means in more detail in clearing the air on VOCs.
It is worth knowing that 500 grams per litre is not an unusual figure, it is the legal ceiling for this category of coating in Great Britain. We have set out what the law allows, and why the number is already printed on the tin in front of you, on what 6.4 grams per litre actually means.
Where Osmo is the better choice
We would rather say this than have you find out afterwards
- Osmo is cheaper per litre, and needs no equipment. A tin, a pad and some patience is the whole kit. Oslek needs a lamp, and the lamp is the significant cost. For a one off job on your own floor, Osmo is very likely the sensible answer.
- Osmo is everywhere. Every merchant stocks it, every decorator has used it, and there are decades of finished floors to look at.
- Osmo does not ask you to change how you work. If the programme already has the drying time in it, and nobody is waiting on the floor, the speed buys you nothing.
The cost question, straight
Per litre, Oslek costs more than Osmo. That is not in dispute.
Per square metre the gap narrows, because of the coverage and the coat count above. Run your own numbers rather than ours.
Where the comparison actually turns is labour and programme. A coating that is finished when you switch the lamp off removes the return visit, the overnight protection and the risk of something landing on a half cured floor. If none of those cost you anything, Oslek will not pay for itself. If they do, that is where it earns back. We have put figures on it in the real cost of slow drying coatings.
Which to choose
Choose Osmo Polyx-Oil if it is your own floor, the job has no deadline, the budget is the binding constraint, or you want a finish any decorator in the country can maintain.
Choose Oslek LED Hardwax Oil if the space has to be back in use the same day, the job is in an occupied building, you are finishing components in a workshop and the drying racks are the bottleneck, or the specification rules out VOCs.
Frequently asked questions
Is Oslek LED Hardwax Oil the same thing as Osmo Polyx-Oil?
Both are hardwax oils, so both penetrate the timber and leave a thin protective layer rather than a film on top. The difference is curing. Osmo hardens by reacting with air over hours and weeks. Oslek hardens under a 395nm LED lamp in seconds.
Can I put Oslek over an existing Osmo finish?
Only onto a properly prepared surface. Abrade the existing finish so the new coating can key into the timber, and test a discreet area first.
Does Oslek really cure in seconds?
Yes, under a compatible 395nm lamp. Without one it does not cure at all, which is why the lamp is not optional.
Is Osmo Polyx-Oil VOC free?
No. Osmo's own data sheet states a maximum of 500 grams of VOC per litre, which is the legal ceiling for its category in Great Britain. Oslek LED Hardwax Oil contains 6.4 grams per litre, because it hardens under light rather than by evaporating solvent.
Does LED hardwax oil smell?
Next to nothing, because almost nothing evaporates out of it. Solvent smell comes from VOCs leaving the coating as it dries. Oslek contains 6.4 grams of VOC per litre and cures by light, so there is no drying period for a room to smell of, which is why it suits occupied buildings.
Which covers more per litre?
Oslek, by a clear margin. Osmo quotes approximately 24 square metres per litre per coat and specifies two coats on new timber. Oslek covers 40 to 50 per litre by hand in one coat, or 70 to 80 by machine.
The quickest way to settle it is to coat an offcut of your own timber and cure it while you watch.
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