Welcome to part 2 of our series on wood types. This week I’ll be discussing oak & oak wood treatments. If you haven’t already read part 1, feel free to go check it out here: All about Pine Wood.
A Little History of Oak
Oak (or quercus as it is known in Latin) is a hardwood with some 400 known species. It has always been a popular wood in the UK, but in recent times it is even more widely used in construction and also as internal fixtures in clubs and gyms etc. For furniture construction, oak has become ever more the wood of choice, a trend expanding year on year since the year 2000 when China, India and Indonesia substantially increased their export markets. Pine has been the wood to suffer from oak’s popularity as it is more widely available in the Far East.
The flowers of many oak trees are known as catkins and they are produced by oaks when they reach their reproductive age, which is typically around 20 years. They are triggered by rising temperatures in spring. Ultimately it is the catkins of many oaks that turn into the acorns, so maybe that popular phrase… ‘mighty oaks from little acorns grow’ should be ‘mighty oaks from little catkins grow’, although it doesn’t quite have the same ring, does it?
Acorn of the mighty oak tree.
Treating Oak Wood
With regard to finishing and treating oak, there are numerous possibilities, but there are certain requirements that are asked for time and again… Often we are asked how external oak can be kept looking natural. Whilst the question is easy, the answer is not so straightforward. These are the necessary considerations:
- When water penetrates oak, it reacts with the high tannin content within oak, resulting in ‘blackening’.
- The sun’s UV rays will turn the oak to a silvery hue over time.
- Clear products are inevitably not completely clear, so they tend to ‘bring out’ the natural colours of the oak, normally making it a bit darker and warmer.
- The levels of rain, wind and sun will make a difference to how quickly the oak changes colour.
Oak turned grey/silver by UV rays & water damage.
Oak barrels traditionally used for whisky and beer.
If the requirement is to keep the oak looking as natural as possible, whilst preventing blackening or silvering as much as possible, then the following is the best system we know of:
- 1 coat of clear wood preservative
- Followed by 2 coats of Osmo UV Protection Oil 420 Extra
Osmo 420 Extra offers UV resistance and also contains biocide which is important for external timbers as it prevents the wood from becoming diseased with wet rot, dry rot and blue stone etc. The oil also repels water, thus preventing it from going black.
If the requirement is to protect the oak whilst keeping the silvery appearance, then the following is the best:
- 1 coat of clear wood preservative
- Followed by 3–5 coats of high-quality tung oil such as Morrells Tung Oil
Tung oil is one of the clearest oils on the market and doesn’t offer UV resistance.
If the exterior oak needs to be coloured, then the following system is recommended:
- 1 coat of clear wood preservative
- Followed by 1 coat of your chosen colour of Osmo Natural Oil Woodstain
- Followed by 1 coat of clear Osmo UV Protection Oil 420 Extra
If blackening on exterior oak needs removing, then scrubbing with a fungicidal wash such as Barrettine Mould and Mildew Cleaner is recommended. On the other hand, it may be the silvering that needs removing. If so, a scrub with Osmo Wood Reviver Gel (which contains oxalic acid, amongst other active ingredients) is recommended.
Unfinished oak.
Treated oak.
One of the most common enquiries we get is how to keep internal oak looking natural. This is not just a case of simply applying ‘clear products’ as they bring out the natural colours of the wood, thus making it a little darker and more golden. A very good indication of how your oak will look once it has been finished with a ‘clear’ coat is to dampen an area by applying some water with a clean cloth or sponge. The look achieved when the wood is damp/wet is very close to how it will look once a clear varnish or a clear oil has been applied.
Some customers like the way oak colours when clear coatings are applied to it, whilst others want it to be as close as possible to how it looks in its natural state. A more natural look can be achieved by using wood oils that have been specifically formulated to retain the natural appearance of interior oak. These products include:
- If an oiled finish is preferred, then apply two thin coats of Fiddes Hard Wax Oil Natural or Osmo Polyx Oil Raw.
- If a varnished finish is preferred, then 1 part Manns Classic Wood Dye can be mixed with 50 parts Manns Extra Tough Interior Varnish.
Clear wax polish is the one exception to the above… If a clear wax polish is applied to bare oak (or just about any other wood for that matter), then the colour is kept very natural indeed. It’s just a question of whether a wax polish is going to be durable enough. Internal doors, for example, are considered, by most people, to be ideal for finishing with wax, whereas a floor will look nice once waxed but regular maintenance is required, so most people don’t opt for wax for this reason.
If the oak needs to be made darker, then Osmo Polyx Oil Tints or Fiddes Hard Wax Oil Tints are ideal because they colour and protect the wood in the same application. It is always good to try and finish with a clear coat if possible because if the wood gets scratched, it is the clear coat that scratches before the coloured coat and therefore the scratch is not as noticeable.
Oiling Consideration
If oak is being oiled, it is a good idea to sand it with sandpaper that is no finer than 150 grit. The reason for this is that the pores of the wood are more open, thus allowing the oil to sink into the wood better. Better absorption equals greater protection.
Interesting Oak Stats
- Oak bark is rich in tannin and is used by tanners for tanning leather.
- Acorns can be used for making flour or they can be roasted for making acorn coffee.
- Tannin dissolves and escapes from the wood. Wine barrels are made from oak and it is the tannin that helps to give the wine its colour.
- Sessile oaks of Europe can reach heights of up to 40 metres.
- Oak trees regularly live to be 500 years old, although 1,000-year-old oaks are also known.
- A mature oak tree can produce up to 50,000 acorns!
Need help finishing a project made with oak?
For more help and advice on how best to finish oak, contact our team of resident experts who are always on hand to help with project advice and product recommendations.
We love to see before, during and after photos of any wood finishing project. If you would like to share your project pictures with us and our followers, you can either send us some photos or share on our Facebook, Twitter, Pinterest or Instagram pages.
469 comments
Hi
I have just had oak work tops fitted in my kitchen and really like the look of the bare untreated oak, I don’t want to put Danish oil on them as it gives a yellowish tint.
What would be the best thing to use that also offers good protection from water etc.
Thanks
Julia
Reply to Julia:
Good Afternoon Julia,
There are two products that you can have a look at, they are similar products and aimed at leaving the wood looking as natural as possible whilst still giving a moisture repellent protective finish.
The first is the Fiddes Hard Wax Oil Natural (https://www.wood-finishes-direct.com/products/fiddes-hard-wax-oil-oak-lightening) this has a slightly high solvent content than the alternative and so will dry a little quicker. And the second is the Osmo Polyx Oil Raw (https://www.wood-finishes-direct.com/products/osmo-polyx-oil-raw-3044) which is made with more natural products and less solvent.
Both contain a minute amount of white pigment to counteract the darkening that you get with a clear product and leave the wood looking as untreated as possible. It is important to try a test area first, as you are applying to Oak, which is a hard wood, so a tighter grain that is less willing to absorb the oil and can sometimes result in a slight white residue on the surface, some people like this some don’t.
If you take a look at these and feel free to get back to me if you have any questions at all.
Kind Regards Samantha.
Hi, I have made an outdoor table from new green oak sleepers which have been drying for a few months, I want to keep a natural look to the surface which has been sanded. I have read lots on this site and see that you generally recommend preservative before oil for outdoor use but I am wondering if this is safe for surfaces where food will be consumed or will it be OK once dried and oiled over? I have kept the whole thing covered with a tarpaulin but some rain got to it yesterday and it has left brown watermarks on the surface which I guess are tannin marks, will oil prevent this once I get it coated? Also as the the oak is dry externally but obviously still holding plenty of moisture inside, will it be able to escape once oil is applied? Looking in the local DIY shop last week there was no sign of Osmo products which you mention a lot but I saw Ultimate Hardwood Furniture Oil with UV filter made by Cuprinol, do you have an opinion on its suitability?
Hope you don’t mind so many questions but I would appreciate your opinion as you sound like you know what you’re talking about and other sources of advice seem contradictory, many thanks in advance, Phil.
Reply to Phil Daley:
Hello Phil,
Ask as many questions as you want, I am happy to help. Green Oak is always tricky as it does take a long time to dry, as a guide one year per 1 inch thickness, and I would not recommend applying anything until the wood is much more dry. You are effectively sealing in the moisture. Oils will allow some of the moisture to disperse but will slow down the drying process considerably and can cause long term problems with the wood. Covering with Tarpaulin will also slow down the natural drying process of the wood.
Often with green wood it is about allowing the wood to weather naturally and so accepting that the wood will change shape or colour as it weathers and dries. So that what you end up with when the wood does dry is a unique.
Once the wood is dry this is the time to apply a coat of preservative followed by two coats of exterior oil. Barrettine Garden Furniture Oil (https://www.wood-finishes-direct.com/products/barrettine-garden-furniture-oil) is suitable for use on your table and although does not specify ‘food safe’ will be fine once dry.
I hope that helps and if you have any questions or need help with ordering please do not hesitate to get in touch via our contact us (https://www.wood-finishes-direct.com/pages/contact) page.
Kind Regards Samantha.
Hi, I’ve just bought a 12 year old house in the Lakes, so there is a lot of water in the air, with picture windows in large light oak frames. These were originally treated with Osmo Oil but have not been maintained and there is now significant weathering and quite deep blackening in the grain in places. Can these be restored, which would be our preferable option, or do we have to resign ourselves to painting or a dark stain? Thanks, Peter
Reply to Peter:
Good Morning Peter,
You may be able to save them yet. Osmo do a great Reviver Gel >>> Osmo Wood Reviver Gel (https://www.wood-finishes-direct.com/products/osmo-wood-reviver) which with a bit of elbow grease can restore the wood to its natural condition when it has silvered. The blackening you have is likely to be the result of water ingress or the natural process of oak and its tannins. And this can be sanded off or wiped over with Methylated Spirits and this will be the problem area, as removal will depend on how deep the staining goes.
If you manage to get the wood back to its original condition then this opens up your options for a treatment of your choice. And if you are looking to use Osmo Oil then the Osmo UV Protection Oil Extra (https://www.wood-finishes-direct.com/products/osmo-uv-protection-oil) is a clear or lightly coloured oil that will slow down the silvering process and with regular maintenance can keep the wood looking fresh.
Or alternatively you could have a look at the Osmo Natural Oil Woodstain (https://www.wood-finishes-direct.com/products/osmo-wood-stain-protector) which comes in a range of colours and should you have some minor marking still on the wood this can help to mask it.
Both are available in sample sizes and I would always recommend test areas first to ensure you like the finish that will be achieved. I hope that helps and if you have any further questions please feel free to get in touch via our contact page.
Kind regards Samantha.
Hi we have a large amount of oak beams inside and oak doors currently treated with 4 -5 coats of liberon tung oil. I was wanting to look at finishing all the oak with a harder wearing coating. ( had lacquer suggested and osma oil.) Iv also have large amount outside that I was going to treat with osmo oil is that the best thing. Thanks dan
Reply to Dan taylor:
Good Afternoon Dan,
Thank you for getting in touch. For the most durable finish you could consider a varnish Manns Extra Tough Interior Varnish (https://www.wood-finishes-direct.com/products/manns-extra-tough-interior-varnish) this is surface sealer that will be hard wearing, comes in a range of of sheens and is non yellowing and low odour.
For a more natural look and feel but still with very good durability you could have a look at the Osmo Polyx Oil (https://www.wood-finishes-direct.com/products/osmo-polyx-oil) this soaks into the surface of the wood and protects, it does have the benefit of being easier to maintain or repair down the line. Just two very thin coats is required for this product and so a little goes a long way.
Both products will darken the very slightly to give what we call the ‘wet look’.
If you take a look at both products and feel free to get back to me if you have any questions. Always try a test area first to ensure that you like the finish that will be achieved.
Kindest Regards Samantha.
Hi, your website is excellent and I have gotten great guidance! I would like your opinion on one matter…I am fitting an oak stairs and I really love the colour of the natural oak before application of a laquer…I feel the laquer yellows the colour but I prefer the natural grey tone to the wood. What is the best way to preserve the natural colour on a stairs?
Reply to Ciara Aylward:
Good Afternoon Ciara,
Thank you for coming to Wood Finishes Direct with your question. Many clear products will highlight the natural tones of the wood and enhance the grain. For a treatment that leaves the wood looking as untouched as possible but still giving a protective and durable finish you could have a look at the Fiddes Hard Wax Natural (https://www.wood-finishes-direct.com/products/fiddes-hard-wax-oil-oak-lightening) it contains a minute mount of white pigment that counteracts the darkening impact.
This product is available in sample sizes and I would recommend a test area first to ensure you do like the colour and finish that will be achieved. if you take a look at that product and feel free to come back to me if you have any further questions.
All the Best Samantha.