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. we have just purchased air dried waney edge oak for our 1900 house to replace the 100+ year old cladding that was on the gable at the top of the house (which was starting to fall off!) The boards would be in a pyramid shape once up so 7x different lengths. We want the boards to age to silver and don’t want the hassle of having to treat it every few years as we are nearing retirement. We aren’t sure if we should be treating it before it goes up with anything to protect it from insects and the weather (it’s a very exposed area in the north west of England with a lot of rain) i’m also not sure if we should be treating it with something for the tannin staining, though maybe this won’t be too visible as it’s high up?
thanks
Sharyn
Reply to Sharyn Mckittrick:
Good Morning Sharyn,
Thank you for getting in touch with your enquiry. I would say your best option will be to treat the cladding before putting up, this way you will be able to apply to both sides of the boards for a better level of protection. A clear preserver will help protect the wood from mould, fungus and rot and with a product such as the Barrettine Cladding Preserver which is ideal for your project.
With new oak tannins are an inevitable issue and if you take the time to wipe over the wood with Methylated spirits first, this can pull out some of the surface tannins and reduce staining. If you do this before application of the preserver, it will not stop or prevent the tannins from coming out, and this will mostly occur with damp, cooler weather, but it will help reduce initial leaching.
The preserver will protect for a number of years however to maintain that protection top up coats will be required at some point in the future, when will depend on how exposed the wood is to the elements.
I hope that helps and should you have any questions please do get back in touch via our contact us (https://www.wood-finishes-direct.com/pages/contact) page.
Kind Regards Samantha.
Hi, I yesterday mounted a brass plaque on a piece of untreated oak board and then onto a wicket gate. the plaque is a memorial plaque to a friend’s husband who died last year. Overnight it has rained and the plaque now has two slight trickle stains down its surface which I presume has been caused by tannin release from the oak. I understand this might go on for 6 months before all the tannin has run out? Is there any treatment for the oak which could minimise or even remove this problem altogether? Many thanks for any advice you can give.
Reply to Roger Jackson:
Good Afternoon Roger,
It is as you say a common issue with Oak, moist or cooler conditions will activate the tannins and this can go on for while depending on the age of the wood. Wiping over well with Methylated Spirits regularly will help to remove and reduce this. And staining however may require a light sand.
Its worth a regular clean as those tannins will encourage black mould spores and these will certainly mark the wood if not cleaned away regularly. It will over time stop occurring but if you keep and eye on the wood for up to 2 years to ensure it is well looked after. And if you need any advice on a product to treat and protect the oak with please do feel free get in touch and speak to one of our friendly advisers via our contact us (https://www.wood-finishes-direct.com/pages/contact) page.
If you have any further questions please do not hesitate to get back to me.
Kind regards Samantha.
i have an oak door which i would like to sand and then oil. i intend to use sandpaper and sand it by hand. i will also use the oils and wood preserves mentioned above. is there anything i should be wary of?
Thanks. wei
Reply to wei chen:
Good Afternoon,
It is vital to ensure that all previous product is removed. The finishing oils need to penetrate the surface of the wood in order to provide effective protection. Any remaining previous treatments may prevent this from happening and uneven sanding will be highlighted when the oil is applied. There are lots of helpful videos on our You Tube Channel >>> https://www.youtube.com/channel/UC7-tgwbsUxm73aVnAjLGHRA?view_as=subscriber with helpful hints and tips on preparation and application.
All the Best Samantha.
We are trying to match a new section of unfinished oak stair case to our existing. We’re struggling to find the right finish and have tried medium and light oak varnishes, which are too brown as well as antique pine varnish which is too dark. The finish of the existing stairs is more of a honey/orangey colour. The handrail has a slight gloss to it, the spindles less so. Any tips to finishes we could try please?
Reply to Claire:
Hello Claire,
Thank you for getting in touch with your question. Colour matching can be difficult, even with the same type of wood, and the age, type and condition will all impact on the colour that will be achieved. Even how you prepare the wood can impact on product uptake and in turn colour.
You could have a look at a stain to get the desired colour followed by a top coat of clear varnish, the Manns Classic Oak Stain (https://www.wood-finishes-direct.com/products/manns-oak-wood-stain) has a wide range of colours available that may come close to the colour that you want, and they can be intermixed to create an alternate colour or lightened by adding water. Its worth baring in mind that the top coat of varnish will slightly darken the colour also and full test areas are recommended to ensure you are getting the desired finish.
If you take a look at those and feel free to get back to me with any questions you may have.
Kind regards Samantha.
Hi I have just put in solid oak worktops in my kitchen and ragged on two coats of osmo poly-x, any slightest bit of water marks it and even if it’s dried up straight away it fur’s up the timber. It was finished to p240 before oiling. What have I done wrong?? Thankyou
Reply to James:
Good Afternoon James,
Thank you for getting in touch with your question. I believe the problem you have had is down to the oil being unable to penetrate the woods surface. Oak is a naturally hard wood with a tight grain and as you have sanded to a 240 grit this has closed the grain further, making it difficult for the oil to absorb into the wood.
When this happens some or all of the oil may have dried in the surface and this will offer little protection and is probably why it is marking so easily. Unfortunately the only way to resolve this will be to remove the current oil and re sand to a 120 – 150 grit, to open up the grain, wipe over with Methylated spirits and re apply the oil.
You may also want to consider a slightly thinner oil, more suited for hardwoods called Osmo Wood Wax Extra Thin (https://www.wood-finishes-direct.com/products/osmo-wood-wax-finish-extra-thin) whilst the Polyx Oil can be used for most wood types the Extra Thin can be easier and just as protective to use.
I hope that help and if you need an further guidance please do not hesitate to get in touch via our contact us (https://www.wood-finishes-direct.com/pages/contact) page.
Kind regards Samantha.