Garden Decking Stains, Treatments & Oils : Part 1 – Getting Started


How’s your garden decking looking? Is it looking tatty, less than its best and in need of a good seeing to?

In our special series of three posts about wooden decking stains, treatment and oils we’re looking at how to make your decking look beautiful and last longer,  exploring the differences between the myriad of products on the market, their application and common sense decking maintenance.

By the end of our third post you’ll know exactly how to keep your soft and hardwood decking in tip top condition from one year to the next.

First… laying your decking the right way around

Did you know you were supposed to lay grooved decking face down? The smooth side is, believe it or not, less slippery than the grooved side, which is actually designed to face downwards. The smooth side also requires less oil than the grooved side because there’s a smaller surface area. Imagine a piece of concertinaed paper that is grooved but then stretched out flat…hey presto! It becomes bigger than when folded. Smooth decking is also easier to keep clean and finish. Apparently The UK is the only country to predominantly ‘expose the grooves’.

About decking

Decking is both useful and good-looking in any garden, but left untreated and unloved will soon start to look tired and worn. The good news? Even if your decking has suffered from the ravages of the British weather, it can be revived without too much fuss by simply following a few basic steps.

When it comes to treating decking there are numerous factors to consider. In this article we’ll address them all, but if you have a specific question feel free to contact us.

Is your new wooden decking pre-treated?

Most new decking nowadays comes pre-treated with a wood preservative that offers protection against wood disease and insect attack. But few, if any, come ‘pre-finished’ with a decking oil or decking stain.

To check if your timber has been pre-treated, look for a green/brown tinge or a surface that’s darker than the inner cut face. Pre-treated decking is sometimes called tanalised timber, or tanalith, which is the industrial name for a wood preservative. If it has already been treated, it’s ready for finishing.

Decking treatment – Is a wood preservative necessary?

Although clear wood preservers don’t contain any pigments or dyes, the ingredients always influence the colour of the wood. If your decking is bare wood with nothing on it at all, applying a decking preservative comes highly recommended for a smarter appearance and a longer life.

What finish is currently on my old wooden decking?

If your decking has been finished already and just needs a makeover, you need to identify the wood’s existing finish. Most decking top coat finishes fall into one of two categories, either oils or sealers, but because manufacturers don’t always use the terminology on the tin, this will be helpful:

  • Decking oils penetrate into the wood and become a part of it, with only a small amount remaining on the surface. The grain tends to show through very well and the wood retains its natural texture. Oil-based decking products are easier to maintain and repair, and most people also prefer to see the natural beauty of the wood grain rather than cover it up.
  • Decking sealers bond and produce a film on the surface of the decking, much like a varnish or paint. Because sealers sit on the surface of the wood rather than penetrating it, the grain is covered up slightly or dramatically, depending on the product. It actually looks like a semi-translucent paint and feels smoother than an oil, without that typical woody texture. Sealers can be problematic because they will at some point start to peel and flake, it’s just a case of when. When it comes to re-coating, you have to remove all the flaky material first, and can only use a similar product on top. If any remains, the finish tends to peel and flake faster because it’s sitting on top of an already unstable surface.

How to remove decking finishes

Once you’ve determined which finish is currently on your decking, it’s time to either prepare it for re-finishing or remove it altogether to start fresh. Your decision depends on two things: what colour you want to achieve, and which finish will give you what you want. Here’s a run-down of each method:

  • Sanding is only practical if the decking is smooth, with no grooves, and you want to completely remove the decking sealer.
  • Jet washing is a popular choice for removing decking sealers that have peeled or flaked with age. Decking oil finishes can also be cleaned this way, but you need to take care not to push the existing finish out of the wood and into surrounding plants, ponds and soil.
  • Remove oil-based finishes with white spirit if you want to retreat your garden decking with a sealer. If you want to re-treat a previously oiled exterior deck with a fresh coat of oil, you don’t need to remove all the existing oil. Just clean the surface with white spirit.
  • Use a varnish stripper if you want to completely remove decking sealer and retreat it with an oil-based product.

In general, if the wood has been treated with a decking oil and you’re happy with the colour, it’s a simple matter of cleaning the decking and re-applying two or three coats of fresh oil.

It’s worth bearing in mind that the colour of the wood will influence the eventual colour of the finished decking. Using a cedar red decking stain, for example, will give you three distinctly different colours, depending on whether the wood is new and untreated, new and treated or old and untreated.

Hard wood decking or soft wood?

Assuming the wood is either new or has had the previous finish removed, knowing what type of wood you’re dealing with helps you identify the best performing wooden decking finish. Exotic woods like Ipe and Bangkarai are naturally very oily, as are many hard woods, and decking sealers don’t perform at all well on oilier woods. If you don’t know the exact wood type, simply knowing whether it’s a hard or soft wood will help enormously.

How to use oil-based decking products

Different hard woods contain different levels of oil. If the hard wood is new or has only been felled during the last few months, it will contain more oil than if it was cut down three months, six months or two years ago.

Some woods, for example Teak, remain oily for longer than others and remain weather-resistant for much longer than soft woods or less oily hard woods. If your decking is Teak, it may be best to do nothing for at least a year then only apply one coat of decking oil or Teak oil.

The best way of knowing whether wood is ready for oiling is to drop a small amount of water on the surface.

  • If the water beads up and sits there, the wood is already nice and oily.
  • If it sinks in and forms a blot mark, the wood needs oiling.
  • If the water sits on the surface for half an hour or more then starts to sink in, there’s already a reasonable oil content and your decking probably just needs one thin coat of fresh oil.

Alternatively, you can use a simple sight test: if the wood looks, dry, patchy, black or grey, it is asking to be treated or oiled, although some people like the look of silvery grey, worn, weather-beaten wood.

If you’ve decided on an oil, the idea is to get as much of the product to sink into the wood as possible so it becomes completely water-repellent. 

How to maintain decking?

Next time, in Part 2 of our Complete Decking Guide, we’ll be taking a look at some of the more common decking problems that can occur, plus their causes and cures.


  1. I have a new deck of pressure treated pine, and there are some bright green stains around the knots from the treatment. How should I handle these when it comes to finishing the deck? Should I let the deck weather and hope the green stains disappear before applying a finish? Should I lightly sand them off at the risk of removing the treatment? Is either an oil-based or water-based finish better at concealing these green stains or allowing them to fade naturally?

    Thanks so much!

    • Hello there!

      The green stains are caused by a preservative treatment put in the boards to protect them from rot and mould. This generally leaks out of the knots in the wood. You can clean these off with some Methylated Spirit directly before application of a decking oil or leave the boards to weather for a short period of time (4-6 weeks) and these will have faded or worn away in this time. Any coloured treatment is likely to discolour near these areas so covering them with a stain should really be avoided.


  2. Hello everyone, I have just built a new replacement deck in Balau which looks stunning in the wet. I would like to preserve the deep red colour as much as possible but realise eventually it will probably go grey like my previous Balau deck did. I have a conservatory built on the deck so they are very linked visually. I used 18 year old Balua vanished with 4 coats of Sikkens which is still beautiful and now the new deck matches when it is wet.
    I had a bad experience on the last deck using an oil product which ended up a sticky film and took years to wear off. I am hoping there is a product that will provide UV protection, keep the colour longer and not become sticky or slippery. The 160mm Balau planks are groove up mostly and both plain and grooved are very slip resistant at the moment. Cheers Phil Hartle SO316NE

    • Hello Phil,

      Thank you for your question. Balau is often used because of its durable structure and appearance even with out a finish applied. It is of course a dense wood and so less willing to absorb oils that are applied. This does not mean that oils are not suitable and in fact I nearly always recommend oils for decking areas as the better and easier to maintain option.

      It does need to be the right oil however, and I would always recommend an Osmo product for these types of wood. The Osmo Decking Oil is a slightly thinner oil than many other decking oil brands and so more suited to these types of hardwoods. 007, from the Osmo Decking Oil range, is a clear option that will darken the wood and highlight beautifully the natural tones of the wood, resulting in that ‘wet look’ appearance. Or the Bangkiria 006 is a coloured option most suited for Balau and the addition of pigment will better slow down the silvering of UV damage. Both should be used in conjunction with the WR Base Coat

      So two thin coats of this can be applied to the wood, after a period of weathering, which needs to be around 12 weeks as a minimum. Then you are able to try a test area to ensure you like the result that will be achieved.

      The previous issue you had with an oiled finish could be the result of the oil being unable to penetrate the surface of the wood, and this is usually the result of over application or the wood has not been weathered for long enough. And a regular clean to avoid the build up of algae will keep the wood slip resistant.

      I hope all of that helps and if you have any questions at all please do not hesitate to get in touch via our contact us page.

      Kind regards Samantha.

  3. I had decking fitted 3months ago that had been treated. I want to put a clear oil on and done a tester spot and the decking went green. What do you suggest I do or am I treating it too early.

    • Good Afternoon Nicola,

      Most exterior woods come pre treated or Tanalised, this is often green in appearance and is because of a copper content in the tanaliser, and over time the colour does wear away. Application of an oil to a new wood will highlight any colours, marks in the wood alongside the natural tones and grain.

      There is not a lot you can do about this but do be assured that it will fade away over the course of the coming year, with out much reduction in the protective quality to the wood.

      Kind regards Samantha

  4. Hi i am putting down a new deck using tantalised boards which have a slight green tint from the preservative treatment i would like to protect them further and tint them to a light to mid brown colour, i do not want to use a paint type treatment as i have used these before and don’t like the appearance, is there a stain type treatment that can be applied by sprayer that is environmentally friendly, i know most of the older types of spray preservatives had some pretty unpleasant chemicals in and was wondering if the technology had moved on to effective but safe water based alternatives, also would you recommend leaving the decking down for a period of time to settle in before treating or is to ok to treat it straight away.

    • Hi Ian,

      You can use a wood preservative such as Barrettine Premier Universal Preserver to further protect the wood from biological threats such as mould, algae, wood rot and insect attack. Once treated and fully dry (24 to 72 hrs), use a lightly tinted / pigmented decking oil to achieve the colour you are looking for. Decking Oils are an excellent choice as they are very easy to apply and maintain. They help to keep the wood nourished and supple and provide excellent weather resistance. Ideally, a fresh maintenance coat should be applied in Spring and Autumn. A couple of good options are Manns Premier UV Decking Oil or Ronseal Decking Oil. Alternatively, you can find our full range of decking oils here.

  5. I wanted to get some advice from you please. Every year, I scrub my decking clean with warm water and mild detergent and then after they are dry, I apply Ronseal Decking Oil. This year, I applied it twice – once in April and again in late September. When I was hand cleaning the deck in September, I didn’t notice any rot at all.
    Last week, I noticed rot, images are below:

    My neighbours who have never cleaned their decking never applied any protection and have green or algae-like coating on their decks don’t have rot, which is odd. I don’t wish them to have this problem, but it’s perplexing that I apply protection and I get the rot.

    I wanted to ask – what would you suggest as remedies? I am thinking of allowing the decking to dry from rain, then apply anti-rot treatment to the affected areas (which are quite small), then apply decking oil again. But, I think it is likely that the decking oil repelled water and caused it to accumulate at nail heads and small cracks which caused it. Most of the rot is at nail heads.
    So I will need to apply something on the nail heads perhaps.

    What, if any, would your advice be?
    I am also thinking of stripping off the old with White Spirit so the rain water does not ‘sit’ on top on the surface and find it’s way to the nail heads.

    Thank you

    • Hello Joshua,

      Frustrating for sure when you put so much work in. It could be a number of factors that include the types of wood, position, surrounding environment. Areas exposed to dampness, such as large foliage or woodlands nearby can wear quicker. My advice would be to continue with your good care and maintenance.

      Applying a Wet Rot Wood Hardener around the area of the nail heads could help it will impact on the Oil that you are applying however and the oil may not penetrate the wood in these areas and you could have a slight variance in appearance.

      Stripping oil can be a little difficult and time consuming, a pressure washer can be an effective way to clean and strip the decking, take care not to hold the nozzle too close however as this can damage the wood and cause splinters.

      I hope that helps and if you have any further questions or need any more advice on products please feel free to email me at

      Kind regards Samantha.

  6. hi i have just installed new decking i have coated it with blackfriars anti slip clear stain,but in some places i have blanching,or whitening. how can i get rid of this,many thanks mick. p s the stain is oil based.

    • Hello Mick,

      I am not familiar with the Blackfriars range, but it could be a cluster of the granules where the product has not been stirred enough. This is just a best guess however and if you are able to send some photos in to and I will happily take a look.

      Kind regards Samantha.

  7. A post Barrettine application question. I have a number of knots leaking a white stain. They have only recently appeared, but do look sad ! Any suggestions ?

  8. Purchased the Barrettine decking oil as suggested by Sam. First class. Very pleased. It was absorbed into the tanalised wood easily.
    Would certainly recommend in terms of application and colour.

  9. Bump !
    Paul Says: Your comment is awaiting moderation.
    July 15th, 2017 at 6:16 pm
    Great advice re what to use to treat tanalised decking boards.
    My question is when ? We have just had 4x4m decking laid. It is tanalised wood. We propose to treat and to darken slightly, but unsure whether we should leave the wood alone for a period. Friends have suggested that it would be best to ‘let it settle’ and leave alone for one winter. What is the professional recommendation please?
    PS Great site !

  10. Great advice re what to use to treat tanalised decking boards.
    My question is when ? We have just had 4x4m decking laid. It is tanalised wood. We propose to treat and to darken slightly, but unsure whether we should leave the wood alone for a period. Friends have suggested that it would be best to ‘let it settle’ and leave alone for one winter. What is the professional recommendation please?
    PS Great site !

    • Hello Paul,

      Allowing the wood the ‘weather’ is often about the wood shifting and moving in the changing weather conditions. Expanding and retracting. If a surface seal, stain or varnish is applied it can end up flaking where it is not flexible enough to stand up to the woods natural swelling and shrinking. Truth is that the wood will continue to do this through out its life, how much may depend partly on the finish and protection that the wood receives as well as how exposed it is.

      For standard grooved decking boards we recommend applying an oil to help to make the wood moisture repellent, this can be done straight away or into the next year. I would suggest applying it sooner rather than later, the only exception is if you have a tropical hard wood such as Ipe or Balau as your decking which naturally has a high oil content.

      My recommendation for a product is the Barrettine Decking Oil, which is available in a clear or coloured finish and will also give some UV protection to your decking. Oils are easy to maintain as you can simply re apply a fresh coat when you feel the wood needs it.

      I hope that helps and if you have any further questions please do let me know.

      Kind regards Samantha.

  11. Hi there
    Bought a can of Barrettine Light oak decking oil and it looks nothing like the colour chart on your website.
    It’s looks more orange than brown.

    Does the natural oak look more browner.

    What’s your return policy if the colour is not as advertised if I buy natural oak?

    How dark is dark oak

  12. Hi Sam

    Many thanks for reply.
    So I need a preservative to be applied to the tanalised decking first (Any recommendations) then a good quality decking oil.

    Don’t want clear so looking at the Barrettine natural oak or dark oak.

    And also like the look of the Ronseal Natural cedar and natural oak.

    Which ones best?

    Also read that water based products are rubbish and i’m best going for solvent based products etc???? Is this correct??

    Got a massive area to cover and really want something thats going to last and look after the decking for years.

    Cheers for your help Sam

  13. Hi there
    I’ve just had installed a massive decking area with handrails etc. (Decking is groves up)
    I’ve been told the decking boards are soft wood and tanalised.
    We’re wanting this to last years so looking for the best way to treat it. The wife likes the look of the grey paint/stain on the market but I’m more inclined to keep as natural as poss and show the grain etc..
    What’s best way of doing things decking oil, decking stain or decking paint.
    Do I need to preserve or protect first before applying the finish.
    Do I need to deal after the finish is on and what the best finish.

    Thank you

    • Hello Mick,

      Thank you for your enquiry. Preservative is the first place to start. This will protect against mould mildew and rot and is available in a clear finish. Then a good quality Decking Oil is the best option for long term maintenance. Oils soak into the surface of the wood and will not peel and flake over time like paints will.

      There are a range of colours available and you should always try a test area first. If you have any further questions please do not hesitate to let me know.

      Kind Regards Samantha.

  14. Hi
    I have found your website extremely helpful.

    I have just installed new Pine decking (smooth side up) and have applied 2 brush coats of Ronseal Decking Oil (Natural).

    I now want to apply a non-slip coating and having read info on your website am thinking of using OSMO Anti-slip Decking Oil Clear .

    Would this be an appropriate product and if so how long should I wait before applying it on top of the Ronseal Decking oIl

    Your advice would be appreciated


  15. Hi
    I have found your website extremely helpful.

    I have just installed new Pine decking (smooth side up) and have applied 2 brush coats of Ronseal Decking Oil (Natural).

    I now want to apply a non-slip coating and having read info on your website am thinking of using OSMO Anti-slip Decking Oil Clear .

    Would this be an appropriate product and if so how long should I wait before applying it on top of the Ronseal Decking oIl

    Your advice would be appreciated

    Thanks Dave

    • Hello Dave,

      You can carry out an oil test a to see if the wood will absorb a further coat of oil. Just leave a drop of oil on the surface for 30 minutes to an hour and if it soaks in then there is a reasonable chance that a coat of the Osmo Anti Slip Decking Oil can be applied. If it remains unmoved then you can wait for 3-6 months and try the test again.

      I hope that helps and if you have any other questions, I am here to help.

      Kind Regards Samantha.

  16. I’m just finishing building a new 6m x 5m decked are using treated softwood boards, newel posts, spindles etc. Do I need to use a preservative given the wood has been pressure treated, or just move straight to an oil product? I don’t need a coloured oil merely a plain finish, and would this oil also do the posts etc?

    • Hello John,

      We do often still recommend the use of a preservative if the wood is tanalised. This ensures all aspects are covered and the wood has the best protection possible. That said if you have guarantees with the wood that show you do not need any further preservative then there is no need.

      Decking Oil can then be applied and it can be used on your other exterior wood also. Always try a test area first and if you have any further questions please feel free to get back to me.

      All the Best Samantha.

  17. Hi,

    Is any oil better that The other?
    I can see you’re saying Holzol but is there any difference comparing with Ronseal for example?
    Any information and suggestions are welcome.


    • Hello Jo,

      It can depend on the project itself and the type and condition of the wood you are applying to. There are many different oils on the market all for different things. If you would like to know which products are best for your project feel free to let me know the details and I will be happy to advice further. Or you can email me via the contact page on our website.

      Kind regards Samantha.

  18. Hi,,

    Do I need to apply preserver AND then oil afterwards to my new softwood decking, which I am ready to install, or just choose one product OR the other??
    They (oil and preserver) seem to do similar things but I’m no expert .. lol
    Which is why I am here, asking for help..

    Thanks :o)


    • Hello Stuart,

      A Preservative will protect from mould, mildew and rot and would be a first coat products. And then we recommend oils for decking as they are easier to repair and maintain over time, and they won’t peel and flake.

      The Holzol Decking Oil is a popular choice and has a range colours or a clear finish that would look great on your decking. Two coats of this will make your decking water repellent and there is not need to strip and retreat, simply ensure the deck is clean and dry and re apply when you feel the wood needs it.

      I hope that helps and if you do have any further questions please do let me know.

      Kind regards Sam.

  19. Hi. We have new decking and wish to oil. Some application containers say we need to leave to the weather for 6 months before action. Is this correct/recommended? Thanks.

    • Hello Neil,

      This recommendation tends to be for new Hard and Tropical woods that naturally have a high oil content. This means that the wood is unlikely to be able to absorb anymore oil. It may be that the wood has been slightly weathered or naturally lost some oil whilst in transit/storage/shop the best thing to do is a small test with some oil out of your kitchen cupboard. Put a couple of drops of vegetable/olive oil on the surface of the wood and leave for around an hour, if the oil soaks in then there is a reasonable chance you can apply 1 or 2 coats of decking oil, if however the oil remains on the surface or is only partly absorbed then the wood is still saturated with natural oil.

      I hope that makes sense for you, and if you have any other questions please let me know – Sam


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