Best Decking Oil Results
Deck Preparation before Oiling | Weathering timber
Previously, I have discussed the problems that people commonly have when they apply Aussie Clear to Merbau decking. As I stated in that post, to achieve the best results, deck preparation before oiling is essential:
- once the deck has been installed, allow 6-8 weeks for it to weather
- weathering of decks allows the resins, tannins, waxes and natural pigments (all called extractives) to bleed out
- the weathering process also starts to open up the timber fibres
All of the points above mean you will be able to apply more Aussie Clear to the timber. Your first application of decking oil will last much longer.
All this theory is very good, but where is the proof in the pudding? I have just finished installing an Ironbark deck under a new pergola at my home. The deck was finished 2 weeks ago (3rd April), and my plan is to allow it to weather for 6-8 weeks before applying it’s first coat of Aussie Clear. This is especially important for waxy timbers like Merbau or very dense and hard timbers like this Ironbark deck.
The extractives bleed is what I’m going to focus on in this first post. This deck is partly exposed to the weather as it is under a pergola. The exposed sections saw over 40mm of rain in the first week of instillation over 4 or so days. In the first photo, you see the timber extractives were drawn to the moisture at the edges of where the weather got in.
Above: you can see the timber extractives that were drawn to the moisture after rain in this Ironbark decking.
The next photo shows a clear difference that 40mm of rain had on the timber that received it. The outer exposed edges are a distinctly lighter colour with the extractives beginning to fade. This is perfect for those outer edges, but no so much for the sheltered decking. So what I have done is simply hose down the deck where it’s not likely to get much weathering.
Above: Note the more exposed section on the left half of the photo is lighter than the right half. The roof line of the pergola is on the outer edge of the main deck, so the path at the top left of the photo is completely uncovered while the left side of the main deck is partially exposed.
So the plan over the remaining 4-6 weeks is to frequently hose the deck down to bleed those extractives before oiling it. The next update will be of the deck just prior to it being oiled and of it being oiled.
As always, this method may not be best if the timber is installed in the middle of a heatwave. In that case Preschem recommends putting a single coat of Aussie Clear down to prevent splitting, checking and cupping. Note though, that this first application will not last the usual 9-12 months for the reasons stated above. Otherwise, it is perfectly safe to allow the timber to weather for 6-8 weeks as you shall soon see. Stay tuned for the followup post.
I have been advised to coat the bottom of my ironbark decking.
I know I had to paint both sides of any wide skirting i put into the terrace houses i renovated and the idea was that the coat stopped moisture from getting into the timber differently.
You don’t seem to have done this.
Do you use the deck wash prior to your final coat
Hi David,
Some people swear by doing both sides of the boards for the reason you mentioned. If there is poor ventilation and rising damp then this is not a bad idea at all. What it will do is prevent the board from swelling on the bottom surface, which can cause the gaps to close and possibly the boards cupping if the top is relatively dry.
In my case, the deck is under the pergola and battons were layed onto concrete. The concrete does slope into a drain so I know what little water gets in doesn’t sit for long. I made the decision based on that, As I had wet the concrete and watched the water drain. I was confident that I wouldn’t run into any real issues and I haven’t. It’s completely up to you, but think about how much ventillation you have and how much rising damp you have based on soil type.
In terms of final coat. It’s Ironbark. It’s a very hard and dense timber. You will only get one application on it especially when new. You can overoil the timber and that leaves a film which scuffs easily. If you can, let it weather first before applying the oil but if you want the underside done, then do that first prior to laying the deck. Don’t oil the top face. Allow it to weather for at least 6-8 weeks.
Te downside is that your first application will only last 6-7 months. This is what happened with mine. It’s due to the hardness and density of Ironbark meaning not as much oil will soak in on that application. You do have a higher maintenance deck. Despite this, I still oil it once a year as the weather during winter is usually terrible in Melbourne, so I don’t use it that oftenand it doesn’t worry me.
But here’s the good news; Ironbark is extremely durable. My deck is 6 yearsold and doesnt have a scuff mark anywhere. It hasn’t splintered and is still rock solid.
In terms of using Grey Deck Cleaner, use it prior to applying the top coat. It will clean and remove any weathering that may occur. I made the mistake of doing that and there was a few dark patches on 2-3 boards as a result. But next season it came good again as I did a proper prep job first.
Always do the prep.
Regards
Rohan Baker
Production Manager
G’day mate , I laid an Ironbark deck and coated it with cutek , I’m not overly happy with the finish . Will I need to strip that back before coating with a different product and what product do you recommend thanks
G’day Eoghan,
I’m back from leave. This one is a little tricky. I’ll contact you via email and aks some more questions.
Regards
Rohan Baker
Hi, I have a grey ironbark deck that is about 15-20years old and in need of some maintance. After sanding it bare and washed, the stunning colour it is showing is fantastic while it is wet with water. I would like to get suggestions as to what product to use to coat it so to retain this beautiful colour. Many thanks in advance.
Hi Des,
I use Aussie Clear on my Ironbark deck (not sure if it’s narrow leaf or grey leaf Ironbark). You’re looking at my deck in that photo before I put anything on it. If you go to this article I did a few years back which, it shows the before and after of using Grey Deck Cleaner to deal with me being slack and missing a season. You will see the result with Aussie Clear.
Bear in mind, Ironbark being so hard and dense, you will only need one coat and it’s very easy to over oil. Wipe off any excess before it drys in about 2 hours. As such it’s also relatively high maintenance. I find that the exposed sections last about 9-10 months. But it’s ironbark. I don’t mind if I miss a season. I know it will scrub up a treat without too much fuss like it did again this year. Best timber on the planet.
Regards
Rohan Baker
Production Manager
Hi there,
I have just had ironbark decking installed/built around a plunge pool. I was going to use Cutek decking oil. I’m so confused as to what I should use – water or oil based. Read another person’s comment above that they weren’t happy with Cutek. The sample piece I did one week ago still leaves colour on hands when you touch it – looks dry but ?? I’m also worried about all the rain we have been having lately!!
Thanks for any advice,
Regards
Linda
Hi Linda,
Your plunge pool will offer some challenges with any decking finish. The chlorine you use to treat the pool will shorten the life of the finish, especially a penetrative oil one. However under normal use of the pool during summer, you should get 5-6 months life. It will look faded at the end but I’m not worried about that, as your deck is ironbark. With any product there will be pros and cons. For a penetrative oil fiish like Aussie Clear, they are.
Pros
Cons