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

How’s your garden decking looking? Is it looking tatty, less than its best, 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 is that 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. We’re on hand 9-5 Monday to Friday to help and even provide a freephone UK landline number:  0800 7818 123. 

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 wood 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 in to 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.

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14 Responses to “Garden Decking Stains, Treatments & Oils : Part 1 – Getting Started”

  1. Neil Says:

    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.

  2. Sam Taylor-Casey Says:

    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

  3. Ian Says:

    What can I add to decking oil to colour it….I need a light coffee colour….thank you.

  4. Sam Taylor-Casey Says:

    Hello Ian,

    We have a range of Oils that come in colours that are suitable for decking, but we do not recommend mixing a stain/ dye in to oils to create your own colours. Natural Oil WoodStain, Barrettine Decking Oil and Ronseal Decking Oil are all good options. I hope that helps and do let me know if you have any further questions.

    All the Best Ben

  5. Stuart Says:


    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)


  6. Sam Taylor-Casey Says:

    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.

  7. Jo Says:


    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.


  8. Sam Says:

    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.

  9. John Says:

    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?

  10. Sam Says:

    Hello John,

    We do often still recommend the use of a preservative if the wood is tannalised. 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.

  11. Dave Byrom Says:

    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

  12. Sam Says:

    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 Anti Slip 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.

  13. Dave Byrom Says:

    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


  14. Sam Says:

    Hello Dave,

    You can apply the Anti Slip over the Ronseal, a test area should be done first to ensure the oil will be absorbed and if not then wait for a month or two and try again.

    Kind regards Samantha.

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