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’ve got a 250 year old oak slab with the bark still on one edge, I’m planning on using this in the bathroom as a counter top for my sink to sit on . It was cut during winter/spring I’m sanding it at present . I would love to know how to treat this so the wood is nourished and it has a rich gloss finish (kinda so it’s inpervious to damp and water ) help and advice much needed and appreciated
Reply to Lee:
Good Afternoon Lee,
Thank you for your enquiry. Even though the wood was cut a few month ago it is possible that it still has a high moisture content and my advice would be to check this first. Sealing ‘Green’ wood can have a detrimental effect rather than a protective one. Particularly with Oak that is high in tannins.
As wood dries naturally over time it can shrink or crack and will change in appearance, weight and moisture levels. Applying a treatment will stop this natural drying process from occurring holding much of the moisture in. As a guide it will take one year per 1 inch thickness for the wood to air dry.
If it is in fact dry let me know and I can offer some advice on which products will best suit your project.
kind regards Samantha.
Hi , i have a number of oak sleepers that are used in my garden as raised bed (8 ) , they have been in place for about 3 years , i applied a preservative about 2 years ago , the garden is small ( raised beds / patio tiles – no grass ) , when the weather is good the sleepers look reasonable in a grey / silver natural state , but when it rains they look black on not too nice .. would like to apply an oil or stain to show a warm oak look all time .. what would you suggest ?
Reply to Carl:
Hello Carl,
Thank you for your enquiry. My recommendation would be to look at Barrettine Decking Oil (https://www.wood-finishes-direct.com/products/barrettine-decking-oil) or the Manns Premier UV Decking Oil (https://www.wood-finishes-direct.com/products/manns-premier-uv-decking-oil)
Although marketed for decking this oil is very versatile and can be used for a wide range of exterior projects. It is likely to absorb a fair amount of the oil, depending on the condition of the wood. And test area can give an indication of this.
The oil will help to keep the wood moisture repellent and so rain will bead up on the surface. Regular maintenance will help to keep the wood looking good.
If you take a look at those products and feel free to get back to me with any questions.
Kind regards Samantha.
Hi, we have a lovely interior varnished oak table that I was hoping to use outside. The top is stone but the legs and supports are oak. The legs are visible all the way up and the ends of the grain are exposed but vatnished. It has been varnished all over.
I will happily leave it varnished rather than stripping back and using the solutions above, but can I? Is that at all possible.
Is it possible to use outside with just the varnish, should I do anything more. I will likely cover during winter and maybe even just when not in use.
Reply to Graeme:
Hello Graeme,
Thank you for your enquiry. An interesting question and one that I can not give a definitive answer to. The varnish applied will be an internal one but will give some short term protection to the wood. And will be protected to some extent for by the table top.
That said my best advice will be to strip the wood back to bare and then use a range of exterior products that include a good quality preservative Barrettine Premier Universal (https://www.wood-finishes-direct.com/products/barrettine-premier-universal-preservative) followed by an exterior oil like Barrettine Garden Furniture Oil (https://www.wood-finishes-direct.com/products/barrettine-garden-furniture-oil) this will help to make the wood moisture repellent and is also easy to maintain over time.
It is also possible that the stone top needs some sort of sealer as this could be porous. I hope that helps and if you have any further questions please do not hesitate to get in touch.
Kind Regards Samantha.
Hi, I have an oak church pew that I’m considering using as an outdoor garden bench. Any suggestions on protecting it please?
Reply to Jon Scott:
Good Afternoon Jon,
Thank you for your enquiry. can you tell me if the pew has any finish on it currently, such as a varnish or oil? Or are you planning to sand back to bare wood?
Sanding back to bare wood will allow you to apply a wood preservative such as Barrettine Premier Wood Preservative (https://www.wood-finishes-direct.com/products/barrettine-premier-universal-preservative) which will help to prevent mould, mildew and rot. You can then apply a top coat product of wood oil such as Osmo UV Protection Oil Extra (https://www.wood-finishes-direct.com/products/osmo-uv-protection-oil) and this will slow down the silvering process of the wood caused by UV damage and repel moisture that causes mould and rot. Both products are clear finishes however they will darken the wood slightly to give a ‘damp look’ and I always recommend test areas first.
If you have a look at the products and do feel free to get back to me if you have any further questions.
Kind Regards Samantha.
Hi, I have recently put on 2 unfinished oak internal doors in the house… the Carpenter advice that if it stains I won’t be able to clean it.
He recommended oil but because I have kids and lots of visits usually teenagers in the house I don’t know what’s best if I need to clean it.
Could you please advise what’s the best? Many thanks.
Reply to Martha:
Hello Martha,
There are a wide range of products that can be used on oak doors including waxes, oils and varnishes, each offering advantages and disadvantages. Hardwax Oils such as Fiddes Hardwax Oil (https://www.wood-finishes-direct.com/products/fiddes-hard-wax-oil) and Osmo Door Oil (https://www.wood-finishes-direct.com/products/osmo-door-oil) give a protective finish that leaves the wood looking and feeling very natural. They require just 2 thin coats, are easy to apply, clean, maintain and patch repair should the need arise. The beauty of an oil is that if the finish becomes scuffed, lightly scratched, worn or dirty, it is very easy to patch repair the affected area and restore the look and finish of the door.
Alternatively, a varnish such as Manns Extra Tough Interior Varnish (https://www.wood-finishes-direct.com/products/manns-extra-tough-interior-varnish) provides a tougher, more durable finish that is easy to clean but more problematic if the doors become scratched or chipped. Varnishes also give a less natural look and feel than an oil.
I hope that the above helps but if you have any further questions please do not hesitate to get in touch.
Kind regards Samantha.