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
Hello
I have got some oak from part of a tree that fell down a couple of months ago. I am going to use 3’-6" poles from it to make a play structure for my boys – maximum length will be about 12’. This it my first major project of this kind and I have not worked with oak before.
Having researched this for some days now, I have come to the conclusion that I will need to use stainless steel fixings because of the corrosive effect of the oak on zinc and regular steel. I am planning to use M10 or M12 threaded bar/rod and SS washers and nuts on most sections and M16 on the really key load bearing elements.
Whilst looking up advice on peeling the bark I came across your very helpful site. Please would you advise me on the following:
1 the best method for peeling bark from oak poles;
2 how I can prevent/minimise cracking. The uprights will need to be about 3’ into the ground and the remainder will be clear of the ground.
3 anything I might have not considered given my inexperience!
Thanks for your help.
Andy
Reply to Andy:
Hello Andy,
Interestingly I have just written a Blog on Children’s Play Parks and equipment, and the maintenance and regulations involved in this. It is mostly about commercial play equipment but does give useful tips about making your own. Its not yet published but keep an eye out in the next week or so. In the mean time stripping the bark from the oak will speed up the drying time and that is when cracks in the wood could start to occur. To remove the bark ( which I have not done before ) I have been advised that you should use a chisel and scrapper and a lot of effort. It is worth applying a Decking Oil (https://www.wood-finishes-direct.com/collections/decking-oil) as this will help to keep the wood nourished and reduce the chance of it cracking.
But before the Oil use a good quality wood preservative (https://www.wood-finishes-direct.com/collections/wood-preserver) to protect the wood from Mould, Mildew, Rot and more. Make sure to really soak the areas that is going into the ground, it will inevitably be the area that will begin to break down first but by soaking in the the preservative and treating with Oil before burying it, you will give it longer.
Any cracks that may appear should not be to much of a problem on a solid piece of Oak, just keep an eye on it not being a finger trap for the children and early signs of decay due to water sitting in the cracks. You can of course fill then in if needed. If you have any other questions do let me know and I would love to see the results of your project if you have time, you can send photos to wood@finishes.direct
Hello, We have recently renovated our living room which includes preparing a fireplace for a log-burner. We have also looked at building control/regulations for relevant requirements. We have placed a solid oak beam the appropriate distance above the log burner, rather like a mantelpiece but it is flush with the chimney breast. It will obviously become quite warm so we would like to know what product we could use safely that is obviously not going to react to the heat. We would like the oak to look naturally darker rather like the example given of the finished door above. Kindest regards Paula
Reply to Paula:
Hello Paula,
One of the best products for you to use would be the Osmo polyx Oil (https://www.wood-finishes-direct.com/products/osmo-polyx-oil) It is a hard wearing and durable finish that will darken the wood in a similar way to the example above. And it is suitable for use on your Mantle as it is heat resistant. I would love to see a photo of the finished project if you get a chance, you can send images to wood@finishes.direct
Hello.
We brought 6 light Oak garden chairs 9 months ago and put the togeather and out in the garden about 3 months ago.They had some sort of coating on them but it appears that it is slowly washing off in the wet weather.I am going to Rub them down and need advise what to treat them with so they are weather protected but still look naturaul.can you advise us on the best treatments so they last
Thank you in advance.
Chris
Reply to Chris:
Hello Chris,
Thank you for your question, the first thing I would advice you to put on is Barrettine Premier Wood Preservative (https://www.wood-finishes-direct.com/products/barrettine-premier-wood-preservative) this will ensure that the wood is protected from Mould, Mildew, Rot and Wood Boring Insects. Once this product has dried you need to use a top coat Oil to protect from UV and Water ingress.
If you would like a clear protective finish then any clear decking oil (https://www.wood-finishes-direct.com/collections/decking-oil) or Osmo UV Protection Oil Extra 420 (Clear) (https://www.wood-finishes-direct.com/products/osmo-uv-protection-oil) are good options, and are perfectly suitable for using on garden furniture. If you are thinking of adding some colour, then a coloured decking oil such as Ronseal Ultimate Protection Decking Oil (https://www.wood-finishes-direct.com/products/ronseal-ultimate-protection-decking-oil) would be good or Osmo Natural Oil Woodstain (https://www.wood-finishes-direct.com/products/osmo-wood-stain-protector) which has a good range of colours.
Hi,
I am considering building a garden pergola out of European green oak. I had assumed to leave it untreated and that it would gradually silver. However I read that it could turn black before silvering. Is that generally a big issue, or a short term thing? Are things like oak fences and posts usually treated in some way, or just left to go black and then silver?
Thanks for your help
Lee
Reply to Lee:
Hello Lee,
Thank you for your inquiry. If any external wood turns black or has any black patches, speckles or marks it is usually a mould forming as a result of water ingress. To avoid this you can use a preservative that will prevent mould, mildew, algea, rot and more. Barretttine Premier Wood Preservative (https://www.wood-finishes-direct.com/products/barrettine-premier-wood-preservative) comes in a clear finish and doesn’t have UV Filters in it, so you will still get that silvering effect without any blackening, and your wood will be protected.
Hi there, the frontage of my listed house is reputed to be of old oak ship beams installed by a ships captain, the very first owner of the property.
My neighbours have been complaining that the beams look dried out and tatry and are no longer black. My neighbour has suggested that I get the beams painted black, but my friend a retired furniture antique dealer said that under no circumstances should I use ordinary black paint but a blackened oil product.
I am at my wits end, could you please suggest a product that will not dry out my old exterior oak beams but will nourish and weather seal them, I am bewildered as to what to use.
Your help would be gratefully appreciated,
Thank you
Angie.
Reply to Angela Giveon:
Good Morning Angela,
Thank you for your inquiry, worry not I can recommend some products for you. Your friend the Antique dealer is right. The first thing that you need to do is remove or work out if there is any old product left on the wood. If you have had paint or varnish on there previously you will need to remove it, as it will prevent an Oil that you use from soaking in. If the Beams haven’t been treated for a while this should be easy enough.
The first thing that you will need to do is use a wood preserver (https://www.wood-finishes-direct.com/collections/wood-preserver). Cuprinol Exterior Wood Preserver (https://www.wood-finishes-direct.com/products/cuprinol-exterior-wood-preserver) comes in a black finish so is ideal for use as a base for a Black top coat product. Using a black or ebony oil based product is preferred as these soak into the surface of the wood to nourish it, are microporous, provide excellent water repellent properties and will not peel and flake over time. Maintenance just requires a fresh coat of oil every few years when the wood needs it. I hope that answers your question and if you have any more please feel free to ask. If you would like a different finish i.e clear/natural let me know and I will recommend the right products for you, and we would love to see some before and after pictures if you are able to send some the email is wood@finishes.direct