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Oil-treated wooden floors: the full story

Richard Aylen looks at what lies behind the natural beauty of an oil-treated solid timber floor, how the oil protects the floor, and why you should choose between oiled and lacquer finishes.

VARIOUS kinds of oil treatment have been used to protect wood for a very long time. Applications include weatherproofing of external timber cladding, finishing of furniture and joinery, and notably for surface treatment of wooden floors.

Most oil products are vegetable based, but pure vegetable oil is not very hardwearing and takes an inordinately long time to dry and harden, so the coatings industry has developed ways of making oils dry faster, cure more fully, and for outdoor use they will add fungicides and UV barriers to prevent mould and early failure.

I want to look at why oils are used for wooden floors and along the way make comparisons with lacquer finishes, which are by far the customer’s most frequent choice of finish. Many people are drawn to the natural look of oil treated wood, so how is this natural look achieved?

Oils work in a different way from lacquers. With a lacquer you have a hard wearing ‘skin’ on top of the floor, so in theory the lacquer does all the work, doing its best to resist daily wear and abrasions, and so the timber will theoretically never be touched. When floor oil is used there is no surface coating at all.

When a floor is oil-treated for the first time or refurbished the first coat of oil is applied generously then given time so soak in. After this, any excess oil is removed so nothing remains above the surface of the wood.

The oil soaks into the wood fibres and fills up the pores, therefore you are walking on the wood itself, impregnated with the cured oil. This is why the surface of an oiled floor looks more like natural wood than one with a lacquer applied on top.

Maintenance methods – comparing oiled and lacquered floors
Given that the exposed surface of an oiled floor is the wood itself you might think this makes it only a low-traffic, rather fragile finish, but the opposite is true. A good example is a large area of oiled hardwood flooring in the main concourse at Copenhagen airport, which is I believe about 40 years old.

This is regularly oiled and looks beautiful despite thousands of passengers using it. To illustrate how this type of treatment is so effective another comparison with lacquered floors may help. With a lacquered floor the surface coating is sacrificial; you allow it to wear out to a certain point and then you reseal it.

Oil-impregnated wood fibres are very wear-resistant, but this begins to fail over time and so the floor needs to be periodically re-oiled. Compared with the process of resealing a floor with lacquer, oiling is significantly quicker and easier – comparable with applying a coat of polish – which most cleaning staff will be familiar with.

While a corporate or institutional client will rarely reseal their own floors, it’s usually well in the capabilities of contract cleaning staff to re-oil a floor. You may need to re-oil a floor more often than you would reseal a lacquered one, but the process is cheaper and quicker and regular oiling means the condition of the floor remains consistent, benefitting from ‘little and often’ attention.

You can also spot-treat an oiled floor with good results – something that can be more difficult to achieve with a lacquered surface.

Types of oil and factory finishes
Until recently a typical floor oil product would be single component, made from a vegetable-based oil with additives to make it dry harder and more rapidly. With changes to solvent regulations and technological advances we now have very low solvent and low VOC products, and a choice between single and two component oils such as Junckers Eco 2K Floor Oil, where a hardener is added to make the oil tougher and more resistant to foot traffic.

When you look at oil products offered by manufactures you may see references to ‘UV’ Oil. This can mean one of two things. Some products described this way contain ingredients that resist the long-term damaging effects of UV light, so they are UV-resistant. These tend to be products that are made for external use where exposure to strong sunlight can cause the finish to break down.

More closely related to flooring however are ‘UV cured’ products where the oil (or indeed the lacquer) is applied to the floorboard in the factory, and it is cured by shining UV light on it.
For the manufacturer UV curing provides a very fast and cost-efficient way of applying the finish. But the other side of this coin is that the durability of the factory finish can be very difficult to assess simply by eye.

For some companies the temptation to reduce manufacturing time and cost of materials can be too great, and what may at first look like a durable oiled finish may after a short time attract dirt and wear off because too little oil has been applied.

When ‘traditional’ ie, non-UV cured oils are used in the factory, some manufacturers, including my own company, increase the penetration of the oil by warming the surface of the board before the oil is applied. Used with a good quality oil this creates a high-quality wearing surface that will give the floor a strong line of defence against wear and tear.

The customer’s safest strategy is to rely on the reputation of the manufacturer. At the present time a large part of the hardwood floor market, in particular engineered wood floors, is manufactured as unbranded products in the Far East and they’re branded by their UK distributors. For many of these products it’s often quite difficult to obtain meaningful information on the finish applied to the boards.

Coloured oils
A significant number of oiled floors will be treated onsite rather than factory finished. Many floor oil manufacturers offer coloured versions of their products, and this can be a good way of customising the colour of the floor. With certain types of timber eg, oak and ash, the pigments can emphasise the natural wood grain, enhancing the grain pattern to a greater extent than can be achieved with a clear finish.

With some types of timber, a coloured oil such as Junckers Eco 2K or Rustic Floor Oil can often produce a more uniform colour than the coloured primers which you would use with lacquer treatment systems. The oil is buffed onto the surface, creating a uniform look whereas a coloured primer needs to be applied with a little more care to avoid roller overlap and stop marks.

In fact, it’s often possible to use floor oil as a primer, then apply lacquer on top. Be aware though that oils and lacquers are not always compatible, so the safest option is to use products from the same manufacturer and to check they guarantee their products for use together. This can be a good choice if the client wants a coloured floor but prefers the maintenance routine offered by a lacquered finish.

Application methods
The usual process for oiling a newly sanded floor comprises two main stages. The first is to prime the floor with a generous coat of oil. The aim at this stage is to get the wood fibres to absorb as much oil as possible. It’s allowed to soak in for 20 minutes or so and then the excess oil is wiped off so there is none laying on the surface. This is a very different procedure from a lacquer finish. When the oil has dried the raised grain is cut back with fine grit sandpaper and then one or two thin coats of oil are applied to provide a uniform colour and sheen.

Later, when the floor shows signs of wear and tear maintenance will usually comprise buffing on additional coats of oil or using client-friendly purpose-made products such as Junckers Maintenance Oil. This is a relatively quick and easy process and can often be done by the client or their cleaning staff.

Special effects – water-popping
Coloured oil can be applied directly to the surface of the floor after it has been sanded, but if you are looking for more creative effects one option is a process called ‘water popping’. This entails moistening the surface of the floor, then allowing it to dry. This raises the wood grain and opens the pores in the wood, which allows more of the oil and pigment to penetrate the wood fibres, giving it a stronger colour.

The technique can be used creatively by using stencils to create subtle patterns by water popping some parts of the floor and not others. The result, even with a clear oil, can resemble the water marks that paper manufacturers use.

What are oiled floors like to live with?
If you are used to life with a lacquer-finished wood floor and you then decide to have an oil treated one there are some small differences you might notice, but I honestly couldn’t say which is better or worse, and much comes down to personal opinion. Aesthetics are usually the main criteria for a client choosing an oiled floor. The natural wood textured surface is often very appealing.

Daily cleaning is largely the same for both types, and includes sweeping, vacuuming and damp mopping or use of a scrubber dryer machine for large areas. Given similar traffic levels you would probably re-oil an oiled floor a little more often than you would reseal a lacquered floor.

This may give the impression of a greater workload, but re-oiling is a quick and easy process compared with lacquering and if you want to only oil part of the floor, say in high traffic areas only, then you can do this without getting a patchy finish. Patch sanding and sealing lacquered floors usually produces a patch of a different colour form the surrounding area.

Over time, given proper maintenance the appearance of an oiled floor mellows in quite an attractive way, and so you will see differences between areas that are highly trafficked and those that are not. Heavily used walkways can have a slight sheen, which will not be apparent in the lower trafficked areas.

This may sound like a negative point but in fact it lends the floor a ‘lived in’ look which is rather pleasant and can appeal in a similar way to the way leather upholstery can become burnished over time and achieves a unique patina.

Pre hand-over treatments for factory-oiled floors
If you are a contractor installing a factory oiled floor you should check the manufacturer’s instructions to see if they recommend any dressings or surface treatments to be applied before hand-over to the client. Applying a surface dressing such as Junckers Maintenance Oil can be beneficial, especially for darker coloured floors where scuff marks and handling marks during installation can be removed before the client takes possession of the new floor.

Oiled hardwood floors have always provided an attractive alternative to traditional lacquered finishes and are likely to remain popular. Modern innovations to reduce drying times and increase durability have helped to drive this along.

Their ease of use and the natural look they give the floor have always appealed to clients and designers. When a timber floor is used with a mix of other natural materials in a building or used in a heritage building restoration for example, an oiled finish can be a good choice.
Richard Aylen is technical manager, Junckers

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