We’ve covered decking finish problems in some detail already. But some issues are more common – and cause more grief – than others. This week we’re going to look at the common problem of stickiness, where for some reason the decking oil you’re applying just isn’t doing what it says on the tin. We’ll also look at how to remove old finishes so you can re-apply lots of lovely oil, and provide sensible advice about what NOT to do!
Wooden Decking
Sticky garden decking – What to do about it
You’re doing the decent thing, keeping your garden deck in apple-pie order. But when it comes down to actually applying the decking oil, or re-applying more coats, everything seems to be going pear-shaped. It’s sitting on the surface instead of being absorbed, and you’re getting into a right pickle. So what’s all this horrid stickiness about, and how do you fix it?
4 reasons why decking oil goes sticky
- Over-application – where the oil isn’t penetrating the surface properly
- Issues around using an oil over a non-compatible product like a decking stain, varnish or paint
- Not enough preparation – for example, trying to use a decking oil over mould or algae
- Problems with new hardwood decking, which is already naturally oily
What’s the problem?
If the decking oil you’re applying has gone sticky and isn’t being absorbed properly, your number one reason – assuming it’s new decking – might be the type of wood the decking is made of.
If it’s a brand-new deck, is it made from hardwood? If so, it might already be naturally oily. Which means there’s probably nothing wrong at all – the wood might be oily enough in the first place or even pre-treated with an oil. Some new hardwoods, especially exotic ones, are naturally very oily indeed, and you might find they absorb very little oil, if any at all, at least until they’ve aged a bit and seen at least 3 months of our famously awful British weather!
Over-application is a simple one. If your deck has been happily absorbing plenty of oil then suddenly stops, it’s probably because the timber is already ‘full’ and can’t absorb any more. All you need to do is stop trying to apply more and wipe off any excess with a lint-free cloth.
Some people try to take shortcuts, or don’t fully understand how various decking products work, for example, trying to add an oil over the top of a non-compatible decking stain, a varnish or even a paint. If that’s what you’re thinking about doing, stop right now – it simply won’t work! Decking oils will only work on bare wood or on decking that has been previously oiled. If your garden deck has been treated with a product that forms a protective film on the surface, sometimes characterised by cracking, peeling or flaking, it will have to be fully removed before adding a decking oil.
Decking Oil Applied
The same goes for mould and algae. It might be tempting to just paint decking oil over the top and hope it disappears, but it won’t work. Mould and algae tend to penetrate into the surface; they don’t just sit on top of the wood. And oiling them won’t kill them off. They’re living things and they will only die when treated with a special wood fungicide and mould killer, such as Barrettine Mould and Mildew Cleaner.
Many of the best anti-fungal products for wood kill the mould or algae and also prevent it coming back, which is an excellent idea and buys you more time in between maintenance sessions.
How to remove decking oil
If you’ve taken things too far and need to remove decking oil, or you want to remove an old decking oil and use a different finishing product like a stain or varnish, how do you do it?
Oils soak into the wood rather than just sitting on the surface, so while it’s easy enough to sand them off at surface level, it’s very difficult to get the product out of the grooves. If your deck is oiled, it’s best to use another oil rather than try to remove it and replace it with a stain or paint. Oils are, after all, the best product for decking because they penetrate the wood and protect it so much better, for longer, than something that just sits on the surface, and they let the lovely natural wood grain show through.
There’s a lot of talk online about getting rid of decking oil and replacing it with stain or paint, but the advice is always the same – it’s a huge challenge and you’re probably best off letting it lie. You could try white spirit or a jet washer but even they are far from ideal. Your best bet is to stick with oils. Here’s why…
- Sanding only works when the deck is smooth, not grooved, and it won’t remove oil from the grooves
- You can use a jet washer to clean decking finished with oil but it comes with risks of its own – you could damage the wood surface or contaminate the soil as the powerful jet of water pushes the finish out of the wood onto plants and into the ground
- If you really want to re-treat your decking with a sealer (even though sealers aren’t the best idea for decking), you might be able to remove your oil-based finish with white spirit… on the other hand you might not, and it’s an awful lot of work
Restored Timber Decking
The easy way – Replacing other decking finishes with oil
Rather than try to remove an oil finish and replace it with something that won’t do as good a job – like a stain or varnish – it’s always easier to remove a non-oil finish and replace it with decking oil. A decking stripper, for example, is a great way to get rid of many decking stains and paints so you can replace it with a lovely oil.
Make life easy with a good decking oil
If you want to re-treat previously oiled decking with a fresh coat of oil – which is what we’d recommend – it’s a much easier job. You won’t even have to remove all the old oil. Just clean the surface thoroughly using a good-quality decking cleaner, which will get rid of the dirt, then re-oil it. 2–3 coats should do the trick. If you’re looking for a great-quality decking oil, we highly recommend Holzol Decking Oil.
How to maintain a perfect decking oil finish for longer
As a rule, the better you maintain your deck, the less frequently you’ll need to re-oil it.
- You can’t beat a simple brush for a start, keeping the wood surface free of mud, soil, leaves and so on. Regular sweeping makes a huge difference to the life of a deck
- Cleaning is your next job, regularly using a [product name missing] to get rid of moss, mould and algae and prevent regrowth for as long as six months
- Re-finish your deck with oil whenever it starts looking tatty or worn, to help prevent damage before it starts to happen
Need help with your decking project?
For more information about decking treatments and their uses, contact our team of resident experts who are always on hand to help with project advice and product recommendations.
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119 comments
Reply to Steele:
Hello,
I am not familiar with this particular product, however slow drying and tackiness is an indication of over application. The oil has not been able to absorb into the wood. To remove you can wipe over with some White Spirit (https://www.wood-finishes-direct.com/products/barrettine-white-spirit) and Finishing Pad (https://www.wood-finishes-direct.com/products/woodleys-finishing-pads).
I hope that helps and if you have any further questions please do not hesitate to get in touch (https://www.wood-finishes-direct.com/pages/contact).
Kind regards Samantha.
Hi Sam,
Thanks for that, two final questions – 1)how often does the oil need to be reapplied?
2) Should the first coat of oil be thinned with turps 5/10%?
Cheers
Simon
Hi Sam,
Any chance you could let me know re above questions?
Regards
Simon
Reply to Simon Moffitt:
Hello Simon,
My apologies for not getting back to you sooner. Sanding in the direction of the grain is going to give you a better finish. Sanding against the grain may be highlighted when treatment is applied. But yes essentially you will need to find a way to get into the gaps as well. All existing product needs to be removed in order for the preservative and oil to be able to absorb into the wood.
Once back to bare wood and clean and dry you are ready to begin application of the treatments. So one or two coats of the preservative and then two coats of the Decking Oil. As long as the oil is kept maintained you should not need to redo the preservative for around 6- 8 years.
As you are treating Oak, you will only need thin application of the decking oil. And I strongly recommend a test area first. Applying a colour will increase the UV protection levels for sure, the darker the colour the more protection you will get. I hope that helps and if you have any further question please feel free to get back in touch or email wood@finishes.direct
All the Best Sam.
Hi Sam,
Thanks for getting back to me. The decking is smooth – when removing finish is it best to use a belt sander rather than a rotary one? a friend of mine suggested a power planer? And what about the sides of the boards, there’s a roughly 5mm gap between them.
If the correct prep and application is done, how often would Barrettine have to be reapplied, given the decking here is oak, flat, exposed and south facing? Would using a coloured oil significantly increase this recoat time?
Regards
Simon
The story here is external south facing oak decking (apparently not pre treated) was laid at client’s (I’m a decorator working on their interior) home in february this year. A coat of (the client thinks) pure linseed oil was applied (apparently dry weather over this time), then a month later 2 coats of cuprinol uv guard decking oil was applied by brush. Then the client noticed whitish areas appearing on the surface, which disappeared when the sun hit the decking. A third coat of cuprinol was applied by spray in may.
Now more than 50% of the surface has greyed, the area under the table is in reasonable condition.
Any ideas what would have caused this?
What’s the best course of action? I’m assuming it’s a sand back to wood and retreat? The client wants to keep the ‘golden’ look of the oak and wants something as low maintenance as possible.
From what you’ve advised above the whitish patches were water suspended in the oil, and as the cuprinol uv guard is waterborne it didn’t work with the linseed oil. So in this case the surface needs to be sanded back – including the sides of the planks? Should a wood preservative be applied after sanding, then the decking oil? What would you recommend as a finishing product for a low maintenance cycle?
Reply to Simon Moffitt:
Hello Simon,
Yes you are right it is likely to be a product compatibility issue with the Linseed Oil and the Cuprinol. And so stripping off is the best option, can you tell me if the decking is grooved or smooth ? You may need to use a pressure washer if it is grooved to try to get the products off.
Once you are back to bare wood, you have suggested the right combination of products in the Preservative and Decking Oil. The silvering is a result of the sunlight on the wood and unfortunately even the best clear products with UV Filters will only give limited protection and would need regular top ups to maintain the UV filters. For better UV protection you need to consider applying a coloured oil, the darker the colour the more UV protection the wood gets.
I would recommend the Barrettine Premier Wood Preservative (https://www.wood-finishes-direct.com/products/barrettine-premier-wood-preservative) and then the Barrettine Decking Oil (https://www.wood-finishes-direct.com/products/barrettine-decking-oil). Depending on amount of use the decking gets and how exposed it is to the elements will determine how often you need to re apply a coat of oil. But maintenance is really quite simple. You should always carry out a test area. If you have a read up of the products that I have recommended and feel free to let me know if you have any further questions.
Kind Regards Sam.
Hello – We had a large deck made of spotted gum built in early 2015. After letting it weather I applied two coats of Intergrain natural decking oil (not water based). The deck extends beyond the pergola and so part of it is not undercover. Two weeks ago I cleaned it and applied two more coats of the same oil. I thought I had left re-oiling for too long because the part of the deck that is fully exposed to the weather was already very grey – however the rest of the deck had kept its colour and was still looking good. Well, after two weeks the deck is still very sticky- except for the part of that is fully exposed to the weather. I understand from the useful comments above that the problem is that I have applied too much oil, which hasn’t been able to soak in. Should I just wait and let it dry with time? or try to remove the excess? if so, how?
There is a real contrast between the part of the deck that is exposed to the weather and the ‘sticky’ part. The ‘sitcky’ part is shiny, whereas the exposed part, while having been brought back to a good colour, is dull looking and looks like it could take another coat! How to achieve and maintain a good, even look? Thanks for any help!
Jim
Reply to jim Neely:
Hello Jim,
The area that has not dried due to over application can be wiped back with some White Spirit (https://www.wood-finishes-direct.com/products/barrettine-white-spirit) to remove that excess. It will dry eventually but on the surface of the wood and so over time is likely to peel and flake.
The area that has greyed significantly is has done so because it is exposed to more UV than the rest and this seems to have happened very fast. Protecting from UV can be difficult and many clear products do have Filters in them to help with this, but it would be fair to say that applying a colour will increase the level of protection and the darker the colour the more protection the wood will get. I hope that helps and if you have any further questions feel free to get in touch (https://www.wood-finishes-direct.com/pages/contact).
Kind Regards Sam.
Hi Sam,
I’m using teak decking as horizontal slatted fencing (reversed to have flat planks).
When installed, the contractors coated it with Rustins Decking Oil, and I used the same oil when applying a second coat a year later.
However, when I went to apply another coat this year, I ran out of the Rustins oil part-way through the job. Unfortunately, I was unable to find the same make, and bought Cuprinol UV Guard Decking oil in it’s place (thinking, in my ignorance, that all decking oils are the same). It was only when I went to clean my brush that I realised the Cuprinol was water based – but I thought no more about it.
Next morning, I checked the fence, and the ‘Rustins’ section looks great, but the ‘Cuprinol’ section looks just as worn/tired as it was before i applied the ‘oil’. I feel as if I’ve made a big mistake with the Cuprinol.
Reading above, it looks like I cannot simply apply an oil-based product over the top of the Cuprinol UV Guard – correct?
So, should I remove the Cuprinol, and, if so, what is the best method/product to use?
Thanks for any help!
Brian.