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
Reply to TonyR:
Hello Tony,
Thank you!!
If it is an interior area that you are treating then you could have a look at the Ronseal High Performance Wood Filler which requires a 50/50 mix with wood dust, preferably sanded from the same wood to be filled. Alternatively, we sell a wide range of interior and exterior wood fillers (https://www.wood-finishes-direct.com/collections/fillers) which are available in single part and two pack formulations and in a range of colours. Its worth remembering that any finish applied over the filler is likely to change the colour to some degree.
Always do a test area first. And if you have any further questions please do let me know.
Kindest regards Sam.
Hi Sam, This is a great website, with loads of really useful information! Our farmhouse has 22 oak window frames that were installed circa 25 years ago. Most of them were treated from new with woodstain (Sikkens HLS and Cetol Filter 7, in light oak), and have been retreated sporadically a few times since, so they are now pretty dark in colour. (With hindsight, the decision to stain them was probably a mistake, as the oak has weathered quite badly, especially on the sills, so any new topcoat tends to crack and peel quite quickly, but I guess we’ll just have to live with that). However, four of the frames were never stained – they were just treated with wood preservative and left to weather naturally. They are now badly weathered – very silvered, with deep fissures along the grain, and some rot in the joints underneath the casements. I’m trying to resurrect them by sanding them down (although the cracks are much too deep to remove altogether) and filling the rotten bits. I had intended to go down the Sikkens route again, but I wonder whether the Osmo UV Protection treatment might be a better bet? Does it work over two-pack filler? And if I were to use, say, 3 coats of 425, how much would this darken the oak? (It would be nice to match the colour of the other windows). Would it make more sense to use an oil-based woodstain first? Sorry for such a long post! Many thanks, Gareth
Reply to Gareth Thomas:
Hello Gareth,
The Sadolin (https://www.wood-finishes-direct.com/collections/sadolin) is a more durable finish that will protect for longer, but as you have experienced, it may crack, peel and flake over time if the substrate is unstable or the finish not maintained regularly enough. At this stage the only option is to remove all of the product, sand the wood smooth to sound, stable wood and fill any holes or splits in order to effectively re-coat the surface. The Osmo UV Protection Oil Extra (https://www.wood-finishes-direct.com/products/osmo-uv-protection-oil) is a good option and far easier to maintain over time. The oil penetrates in to the surface of the wood so will not peel and flake. To maintain the surface, simply clean and re apply a fresh maintenance coat as and when required, usually every 2 years or so depending on weathering and the exposure the property has to the elements.
If the window sills are not sloped to allow water run off, any finish is going deteriorate quicker than a finish on a sloped window sill. For surfaces that are prone to standing water, damage is inevitable without continual care. For the colour, a test area is recommended as the natural colour of the wood will have an effect on the overall colour of the finish. Osmo Oils are available in sample sizes for testing product suitability and colour. For areas that require filling, take a look at these wood fillers (https://www.wood-finishes-direct.com/collections/fillers) taking care to ensure that you pick one that is suitable for exterior use. Two part fillers provide the best strength and durability, can be sanded smooth, nailed and screwed if required. I hope this helps and feel free to let me know if you have any further questions.
Kind regards Sam.
Hi,
I have bunk beds made from oak from the look of the picture above it looks like my beds are finished oak. My carpets got wet and the legs of the bed have soaked up some water because the legs are looking black and has green mould on it. Is my bed ruined now and would cleaning it with vinegar be enough? Thanks for your input.
Reply to Mannie:
Hello Mannie,
Water ingress will often cause mould to develop and we have a really good cleaner that will help. Barrettine Mould and Mildew Cleaner is an effective cleaner that will remove mould, algae and kill the spores within the wood. Once treated allow the wood to dry out before resealing. If the mould has stained the wood you may find that the effected areas may require a light sanding and then retreat the legs with whatever is currently on the rest of the wood i.e a wood oil or varnish. Feel free to email me with some photos and further advice at wood@finishes.direct
Kind regards Sam.
Thank you Sam I have ordered some sample colours to try.
Hi
We have just purchased a golden oak Edwardian dining table, it had a few blemishes and an uneven colour.We have sanded it back to the original ‘bare wood’state ,but are now a little unsure how to finish it.My thoughts on reading your blog post are a stain to give it back its golden colour and then a wax/oil of some sort to seal it and give a sheen to the top.But I am slightly bewilderd by the choice. Any advice would be great, on the best products to use to ensure the table is well sealed and a good colour. Many thanks
Ellen
Reply to Ellen:
Hello Ellen,
You could have a look at the Fiddes Hardwax Oil Tints (https://www.wood-finishes-direct.com/products/fiddes-hard-wax-oil-tints) which will colour and protect the wood. It is easy to maintain and to patch repair should the need arise.
If there is not a colour in that range that you like, you could have a look at the Manns Classic Oak Wood Stain (https://www.wood-finishes-direct.com/products/manns-oak-wood-stain) to give the colour and a top coat of Fiddes Hard Wax Oil (https://www.wood-finishes-direct.com/products/fiddes-hard-wax-oil). Test areas are the key to getting the right finish and all the recommended products are available in sample sizes. If you have any further questions, please do let me know.
Kind regards Sam.
Hi,
I need help to fix a scratch on my distressed oak white washed dining table which is finished in a clear non shiny lacquer. when I scratched it I wiped a furniture oil on it which was made the scratch darker and more red. How can I fix this so it doesn’t compromise the look of the table but not draw my eye to it.
Thank you!!!!
Reply to Rebecca Elstn:
Hello Rebecca,
Are you able to send me a photo of the scratch and a larger area of the table without artificial light shining on it to our email address which is wood@finishes.direct and I will be happy to take a look and see if there is anything that I can suggest.
Kind regards Sam.