Aussie Clear on Merbau decking
decking oil | timber finishes
One of the most common mistakes when people apply Aussie Clear as a decking oil onto new Merbau timber, is that people don’t properly read the application instructions. The instructions read: “allow new Merbau timber to weather for 6 to 8 weeks prior to applying Aussie Clear” and “… any excess oil remaining on the surface after 2 hours should be wiped off.”
The reason for this is two fold:
1. Merbau is a very resinous timber.
If the timber is new then when you apply any decking oil product, those resins will mean you won’t get as much of the oil into the timber. It is preferable to allow it to weather for 6-8 weeks, or wash it regularly with fresh water if under cover for about the same period. It’s the water that bleeds the resins out of the timber. In other words, timber finishes work best when you allow the timber to weather. When you do this, your first application of Aussie Clear will be a proper “dose” and should last between 9-12 months (depending on exposure).
However, there is one exception to this where Preschem would recommend oiling the timber straight away, and that’s if the deck has been completed in the middle of a heat wave. In this instance, put one very light coating of Aussie Clear down immediately, as this will prevent the timber rapidly drying which can cause dimensional instability resulting in cupping, splitting and checking. However, this light application will not last all that long for the reasons explained above, so you will need to reapply sooner than what would normally be expected.
2. Aussie Clear that hasn’t soaked in after 2 hours will form a semi-gloss film.
When applied correctly to a timber deck using a lambswool applicator, Aussie Clear decking oil will not form a film. If there is an excess on the timber, then that oil forms a film on the timber if it’s not removed with a clean dry rag. This film actually looks quite pleasing, so the common mistake is to keep re-applying the oil until its a “nice” looking finish. This film can occur with any timber, but is more likely to occur with new Merbau due to it’s high resin content.
The problem with this is that the film is not durable. It’s very easy to scratch and scuff the surface, which is a common complaint when this occurs. This is especially true on a hot day, as the coating softens significantly with heat.
Aussie Clear is designed to be a true penetrative matte wood finish. It will protect and enhance the timber through it’s proven formulation by:
- protect against UV weathering
- improve dimensional stability by controlling moisture content
- prevent unsightly sapstain/bluestain moulds
- enhance the natural beauty of timber season after season with regular maintenance
I was unsure what exactly I’d need to do to apply decking oil to merbau timber but this post has given me confidence in what I would need to do. I’ll have to keep in mind that a 6-8 week weather period for the wood is preferable. I’ll need to take care to avoid a film forming on the wood, like you warned. Thanks for the helpful info.
I am a builder and have been reading all the data sheets from companys and the forums etc. Your explanation is by far the clearest.
Hi i have recently had a Merbau decking built i have been wetting it down to allow it to weather but i went out this morning there was a sticky jelly lump on my deck i tried to wipe all off but there is now a round dark stain any thoughts on how to get off or can i simply sand off thank you
i have recently had a Merbau decking build around pool, like to match same color as fence. Can i paint on my new Merbau decking, when would be good time to paint and how many years would last after painted?
Hi Jenny. Thank you for your question. Firstly, Aussie Clear is not a paint but rather a penetrative oil. Unlike a paint, it will leave the timber looking and feeling like timber. A paint is a solid colour coating.
In terms of your pool, this will be a more maintenance intensive situation than other decks, especially if the pool is used a lot. The chlorine in the treatments (either sea salt or hypercholorites) will break down the Aussie Clear more rapidly, as it is very aggressive to any penetrative oil finish or paint system. So if you follow the advice here and in other news articles on the Aussie Clear in our website, I would estimate that you would get about 6-9 months per application. And if the pool is heavily used, it could be soon as 4-5 months. So it’s hard to say.
I hope this is clear at this point.
What do you do if you’ve already applied the stain oil on construction?
thank you for your question. So you have already applied Aussie Clear to the decking? Has it been over oiled and has left a film as mentioned in the article and formed a film?
Hi same problem for us. The decking man has oiled without letting any season time (same day as laying). mostly fine but has formed some patches where moisture has come up and/or settled and now it looks like dried puddles of pee in patches – you know, like watermarks on paper – help!
Hi NS, thank you for your question in relation to this common problem. I think you are experiencing “extractive bleed” where the moisture from the rain or a hose etc is drawing it to the surface under the Aussie Clear. I hope this makes sense.
There are two ways to deal with this:
1. Leave it be and then when it’s time to reapply in 9-12 months time, do a careful preparation job on the timber using Preschem’s Grey Deck Cleaner. Note though that you may find the deck looks like it needs re-oiling sooner than this. Ignore that and ride it out for 3-4 months. If it’s Merbau or a drable Australian native timber like Iron Bark, Spotted Gum etc, don’t worry, it’s highly durable and will be fine. It just may go a little grey. The oxalic acid in the Grey Deck Cleaner will clear that up nicely. Then re-oil as per directions on the label.
2. If you’re wanting the perfect finish, then you have to sand it back and allow it to weather. Personally, this is overkill and a lot of hard work for not much gain. It’s not a train wreck so if it were me I’d go with option 1.
Enjoy your deck. It should last you for years to come.
I have just finished laying some merbau decking in 40 degree heat over 2 days but it also started raining heavily for about the last 2 hours as I was finishing and rain is forcaste for the next 4-5 days. What would be your recommendation
Thank you for you’re enquiry.
As we are in or fast approaching the business end of summer, then I recommend that you apply one coat only of Aussie Clear now to stabilise the timber. This will minimise the moisture loss on the sun exposed surface, which will reduce (but not entirely stop) dimensional stability issues like cupping, splitting, checking.
But as the resins of “extractives” haven’t really had a chance to bleed out, this means that the timber won’t hold as much of the Aussie Clear as it would if it’s had 6-8 weeks of weathering. You may get 5-6 months life only.
And if you’re likely to get rain within 24-48 hours of application, then postpone oiling until the weather picks up. This can cause other issues.
I have some articles here that discuss this and in particular the issues with Merbau, which is a difficult timber to deal with when new.
Aussie Clear and Merbau Decking
How to Obtain the Best Decking Oil Results
How to prepare your deck for staining
As I am not close to an Aussie Clear stockist, following a good sanding and wash down, will Cabots Danish oil cover my Jarrah outdoor table and chairssatisfactorily instead? Your advice will be appreciated.
I recommend that you contact Cabots to get technical information on their products. I do not know the details of their product formulations or the suitability for this situation. If this furniture is an outdoor setting that’s partially or fully exposed to the weather, then be sure to mention that as this is an important condition when choosing a finish.
fantastic, informative site – clear advice with sound reasoning.
Thank you Jenny.
Hi, I have a new Merbau decking, largely undercover, and will allow it to weather for 8 weeks before oiling. My question is in regards to the frequency of hosing it down during this period. Is a hose down once per week sufficient to bleed out the resins over this time, or should I hose it down more frequently?
Sorry for the delay in response, I’ve just come back from leave.
I would hose it down as often as possible. The more you do that the better it will be as you will bleed more resins therefore get a better result from your first application.
With my largely under cover Ironbark deck installed in April 2014, it was left until September till I oiled it. Came up great when I did it. Like Merbau, Ironbark is very high natural durability, so it has a probable above ground life of greater than 40 years. 3-6 months of weathering will be without harm. Just be sure to clean it with Grey Deck Cleaner before you apply and the results will be terrific.
One thing to note. If you have the 135-140mm wide boards, they may cup a little. This is natural on such a wide profile. In that case, treat it like it was installed over the height of summer. Put a very light application of Aussie Clear on now to minimise the cupping, then let it go for 9-12 months even it if looks a little dry and hungry. This will then become the bleeding process.
This seems like a basic question but I’m in two minds about all this advice with weathering decking. I’ve put up some merbau deck boards as screening, and I love the rich red colour of new merbau. However I realise from experience it’s not possible to stay like this as tannins leach out in the rain. Problem is I just find if I leave it to weather it eventually just loses this lovely colour. A previous one I put up last year was weathered and coated with a similar clear water based deck coat, but it always looks washed out and more grey compared with the new one, and my temptation is to sand it back to renew the colour. So qn is how do I have both, I.e. rich colour of new merbau but follow the advice of weathering? Is it just down to choosing a better oil? Thanks
Hi Adam and thank you for your enquiry.
I do have a detailed post up about why timber changes colour and thats a good place to start to get your head around this.
Weathering new Merbau is essential to acheving a good result. Yes the colour will fade as the pigments wash out, but that’s a different process to UV weathering, which turns timber grey. Allowing the natural resins to bleed out of Merbau will mean that a true penetrative oil like Aussie Clear will last longer, because more of the oil will soak in.
Eventually all water or oil based products will eventually weather grey. This type of finish requries more maintenance to look good that an estrior paint.The big advantage about a try penetrative timber oil like Aussie Clear, is that it’s very easy to prepare the timber for recoating. This post is of my deck where I missed a season, but all I did was hit it with Grey Deck Cleaner and a pressure cleaner the day before and you can see the before and after results.
I’m about to have new Merbau decking put down and I plan to oil it myself. I note your comments about allowing the deck to weather for a few weeks. I’m wondering if that also applies to kiln dried Merbau? If the answer is yes, is there any way I can speed up the weathering process because I want to oil it as soon as possible? There’s a roof over it but some parts are exposed to sun and rain and it’s in Queensland so high UV.
Great to see you supporting your product by answering these questions.
Hi Michael, thank you for your enquiry.
In terms of your kiln dried Merbau, this won’t decrease the extractive content. Therefore your Merbau deck will still bleed. so my recommendation is to at very least, hose the deck down for 2 weeks to bleed at least some of the extractives. And then the day before you decide to apply Aussie Clear, use Grey Deck Cleaner, which will assist in bleeding even more extractives. Please read the label of this product before use and here’s a pro tip: to make up the solution, dissolve the crystals in hot water so it takes 20 seconds of mixing and not 10 minutes.
Also given that this won’t be a substitue for a full 6-8 weeks of weathering, please remember that the performance of the first applicaiton won’t be as high as usual, as the timber won’t absorb as much of the Aussie Clear. I would suggest that the weather exposed parts to last 6-9 months with the first application.
I hope this clears things up.
I find your posts very informative..thank you for clearing up a lot of questions.
I just install Merbau decking last week…i intend to weather it but have also come across those products with Sodium Percarbonate that claim to speed up the process and could do it over two days…do you have recommendations for these?
Also if we water it down…would it leave water marks and/or foot marks..if so will it come off?
I am in Melbourne..
Appreciate your assistance.
Yes, Sodium Percarbonate can also be used as a wood cleaner such as the Woodbrite product and is one product that is used as a “Sap Stripper”. Sodium Percarbonate when dissolved becomes hydrogen peroxide. So it’s caustic and this is what removes the “extractives”. It is in effect a chemical soap, but it also has a bleaching action, so it appears that it’s bled out the resins and colour more than what it has. Look at the post on why timber changes colour. Don’t worry about that as Aussie Clear will restore the colour.
The short answer is yes they will begin to remove the “extractives” from wood, but it’s still not quite a substitute for weathering. So if you are wishing to apply a finish and have the deck ready for Christmas, then yes by all means use such a product. BUT you may still find that the first application won’t last quite as long as you thought (maybe 6-9 months, hard to say). If that’s the case, let it weather for another 3-4 months anyway. Merbau will bleed for some time. So make up for that time at the ned of the first applications life. The maintennace re-application will then last much better.
And you still get the bragging rights on Christmas Day.
i used Aussie clear about a month ago, on my 7 year old merbau decking.
i stain it every 12 months or so with Aussie clear, and generally comes up a treat.
but this time it has left a milky film, or a light dirty looking layer on the top, mostly on areas that cop the afternoon sun.
my neighbour who is a painter thinks i have put it on to thickly this time with the lambswool applicator?
i have started to pressure wash it, and with a lot of convincing, it starts to clean??
the area is about 40 sg metres so it will take me a long time to try and clean.
do you have an easier solution for me??
Sorry for the dealy but you posted this after we had gone on Christmas leave. I’ll followup with an email offline as I want to ask some questions first and get you to send me some pictures.
Hi I’m in North Queensland and my merbau deck has been down for 6 months. I have not put any thing on it as yet-I lnow I bed to sand and clean it- because the timber has aged will this product be beat or should I stain it!
It’s in full sun also. Thanks for any advice as I have read through all the posts but none are the same as my issue
Sorry for the delay in response. It’s been frantically busy here at Preschem. We have been recognised as an official essential supplier (for the power companies) and that’s added to the workload…
In answer to your question, don’t sand the deck. There is no need. You will essentially be back to square one. Once you sand off the very top weathered layer, your’e getting back to “new” unweathered timber. To prep your deck, use Grey Deck Cleaner as directed to remove the UV weathering. I have more detailed information on that with this news article.
I am building a two story house with a kwila deck stacked on each level. If I use a cleaner in the new timber then I will damage other surfaces around it such as the colourbond cladding and the painted pine joists under the first level deck. (The pine is visible from the ground level deck and painted to match the colourbond)
Q: will I get tannin stains if I naturally weather the timer and by doing this method; will I achieve a good/same result as if I use a deck prep wash?
Merbau is a very resonous timber as mentioned. Probably the highest ammount of “extractives” of any available in Australia. Bleeding will be an issue for possibly up to 12 months or more and this is a process you’ll just have to live with.
Tanin stripper products can be made from chemicals such as the mildly caustic sodium percarbonate. They will assist bleeding the tanins but won’t be 100% successful, especially with Merbau. Again, Oxalic acid will also achive some mild strippping of the extractives, but not quite as much as the sap stipper.
Oxalic acid is fine for use on those surfaces provided you wash them off once completed. It will only be an issue if you leave it on other surfaves for days or weeks.
6-8 weeks of weathering is still king. If you go the other route what will happen is you won’t get as much Aussie Clear in the timber, so the first application won’t last quite as long. That’s not a train wreck, just that you may have other expectations.
Thank you for the advice.
Hi we’ve had a new merbau deck built about 4 weeks ago (outdoors). we were told to hose it every day for 10 mins for 2 weeks and then wait another 4 before staining so we’re waiting another couple of weeks or so before doing that. we’ve also had rain during this time and their are noticable water stains in certain parts of the deck. what do you recommend we do to get rid of the water marks?
Water stains are not permanent. Allow your timber to weather for the 4 or even 6 weeks won’t hurt. On the day before you plan to oil it, use a jar of Grey Deck Cleaner to wash the deck down. This will remove all the water marks, strip out some more of the extractives and then leave the timber ready for oiling. Make sure the deck is dry when you oil so as it’s winter, wash the deck first thing.
Also don’t oil if it’s likely to rain within 24 hours to prevent a water in oil emulsions, which looks like isced coffee milk.
Hi, I’m in Melbourne and have just had a Merbau deck installed using 140mm boards. The areas is completely exposed to the elements. Should I treat this in the same way as you’ve recommended and wait 6-8 weeks for weathering before oiling it? Once it’s ready to oil do I need to use a tanin remover product or just a deck wash?
I found with my deck that I should have used the Grey Deck Cleaner to remove some of the weathering that had built up. Grey Deck Clenaer will remove some of the tanins and extractives, but perhaps not as much as a tanin remover would. However nothing will remove all the extractives that Merbau contains. This species contains the highest amount of resins in any commercially available timber in Australia. It takes some time for the resins to bleed out.
One thing to note, being such a broad board, when the timber expands with moisture content, it can cause the gaps between the boards to close up depending on how much gap has been allowed for. This can cause pressure and the deck can buckle or the boards at least cup. It may be wiser to use your tanin strip product now, then apply one coat only to minimise this from occuring while it seasons. Note that this application won’t last very long, maybe 6 months at best. Then when spring hits and the weather changes, then do a full maintenance on the deck to bring it up looking like new for the spring and summer where you can enoy the deck properly.
I’ve recently had a fence built out of merbau and understand I need to wait 6 – 8 weeks before oiling it. Can you please tell me do I need to apply a cleaning chemical first? And will it kill the plants at the base of the fence?
Yes it’s best to allow the timber to weather for 6-8 weeks. If you remember to, wet it with a hose as well. You’re wanting to bleed the resins out of the timber and this will help. When you apply the Aussie Clear you get more oil into the timber and the finish lasts longer.
In terms of cleaning the timber first, if you want a great result straight up, then personally I would. But it’s not critical in your situation. Use Grey Deck Cleaner which is an oxalic acid timber cleaner. This naturaly occuring acid found in many plants/vegetables like asparagus and will break down in the soil quickly leaving no trace. You will only have issues if your plants are pH intollerant, like some species of Camelia’s or Hydrangea for instance.
Having said that, there are two things that will be a little different in your case. Because it’s a fence, and vertical, it will tend to need less maintenance. Also if you do overoil it, the timber won’t have the abbrasion effect of feet and/or furniture on it, so if you do overoil it, it’s not as likely errode like this deck has.
Im in Brisbane and just about to chop and use a whole bunch of merbau slats for a screening Fence around my patio. These will have gaps/spacers inbetween but both ends of the merbau slats will be Sitting inside aluminium channel/posts.
When is the best time to oil/stain the slats? And will the bleeding be easy to clean off the concrete/pebblecrete? Should i let the slats wet, dry & bleed before I install them into the fence or can I install now and stain later??
I’m not keen about the use of the slats sitting into channels. The reason being that the bottom channel will fill with grime/dirt and it will allow water to pool. This will mean you are creating a defacto in-ground environment for the bottom of the post. Merbau is not durable in-ground contact (class 3, or 5-15 years probable life expectency) but is a class 1 above ground (40+ years probable life). In addition to fungal decay, you will likely have issue with sapstain mould as far as the water pooling in the channel wicks up the slats. This effect could also possibly occur at the top channel-slat contact point as well. Ideal you will screw the slats ont othe frame without a channel on the top and bottom. Like a picket fence.
In terms of weathering and resin (extractive) bleed, this could take some time as in up to 6-8 months. It will occur after you apply Aussie Clear as well. But the extractives are water soluble, so the good news it’s not permanent on concrete. A pressure cleaner should remove most of it or perhaps use sugar soap. But give it 6-8 weeks minimum to weather before applying Aussie Clear. And use Grey Deck Cleaner as part of the prep process to get a brilliant first result.
Thank you for your great blog
Hi. We’ve just had a Merbau slat screen built in our garden. The screen faces northwest and cops a lot of sun. How long would you recommend we leave it weathering before applying an oil? We would prefer to oil it as soon as possible as the screen sits behind travertine pavers and we are worried the resins will stain the pavers? I’ve had a lot of conflicting advice and was wondering what you would suggest? Also, someone recommended Sikkens to us, but I’ve read some bad reviews. What is the advantage of Aussie Clear over Sikkens? Thanks!
As it’s not hot yet, allow the resins to bleed for 6-8 weeks. Yes, it will stain your pavers but these resins are water solluable. So either a sugar soap solution and elbow grease with a scrubbing brush will remove it, or a pressure washer. It’s the joy of owning Merbau as it contains a lot of resins/extractives. This bleeding process will take some time and will still bleed even when Aussie Clear is applied. Expect it to alleviate in 6-12 months.
Sikkens products are excellent and the chemistry they employ is unique and very clever (I’m a Chemical Engineer so I do get excited with this type of thing). It’s a case of people not correctly preparing the timber, or leaving the maintenance re-application far to long, or unrealistic expectations. If you leave it too long, you have to sand the Sikkens back and start again as per their directions. But if you’re following all their directions, I can assure you they work well as stated. Leaving it too long between maintenance is Sikkens’ only issue. You need to take this into account with your decision on choosing a product.
I think the advantage that Preschem’s Aussie Clear has is that it’s a lot more forgiving if life gets in the way of scheduling in your maintenance. It’s simple to restore the UV weatheirng and re-oil and there’s no sanding required. Plus as it’s not film forming like Sikkens, so it looks and feels like oiled timber. Sikkens will look more like a satin varnish. Aussie Clear will will fade over time and won’t last as long as Sikkens (about 12-15 months in your situation). These are the pro’s and con’s of Aussie Clear vs Sikkens.
Hi, very informative.
My question is around our new Merbau deck. It was installed as part of a general house renovation which is nearly finished. The deck became somewhat of a place to leave boards and my hose reel for over a week. After they’ve been moved the outline of the boards is left and the marks from the metal hose reel are there. It’s almost like stains.
Can these marks be removed / cleaned off? Coming in to Summer would you recommend treating the deck now or waiting? Thank you.
Without seeing any photos, you have two issues going on with this deck
1. The boards which have left marks are pure water marks. Merbau is a highly resinous timber and it bleeds these resins of “extractives” when exposed to moisture. As the loose boards covered part of your finished deck ,they will somewhat protect the area underneath it. so you will notice that where the boards were sitting, they will be lighter. This is in effect a type of water stain. It is not permanent. But it may take time to fade naturally.
If you don’t want to wait, then recommend that you simply allow it to weather for 6-8 weeks naturally. If it’s under cover, hit wt with a hose or pressure cleaner (only with a car cleaning attachment). Prior to oiling, prepare the timber with an oxalic acid based cleaner like Preschem’s Grey Deck Cleaner. By then, most or all the water marks will have disappeared or be hardly noticeable.
2. The metal hose reel has left what’s known as iron staining. On this section I recommend you give it a very light sand, taking care to not leave the sawdust on the deck. Use a vacuum cleaner or clean dry rag to rub it back. Then wet the section again. You do this to ensure that you have removed all the iron from the timber. Repeat until it disappears. And then hit it with Grey Deck Cleaner.
Note that I have covered some of these items in other posts here and here:
Hi loving your advice,
We have just had blackbutt decking installed during renovations to our house, our builder did recommend deck cleaner and light sand prior to oiling. Did not mention weathering though, so i take it the same as most of the replies given 6 – 8 weeks. Also I read sanding not recommended prior to application?
Thanks in advance
Thank you Brian,
I generally don’t recommend sanding timber unless there is an issue with it such as mill glazing, it becomes fibrous, or it’s stained with something that can’t be removed with Grey Deck Cleaner and some elbow grease. By using an oxalic based timber cleaner on new timber, it will approximate 2-3 weeks of normal weathering but not a full 6-8 weeks. The key is rain. If it’s relatviely dry where you are. I would be hitting that timber with a hose. All you’re trying to do is simulate rain. So wet the timber with a spray setting and this will assist greatly with the “Extractives” bleed.
But I don’t recommend this if it’s stinking hotor liekley to be during that period. The heat and wetting together is a bad combination for dimensional stability. The shrinking/swelling when it dries then wets will be extreme and that’s when the timber can warp, cup and split. In that case I recomend one coat only, to allow the timber to season gracefully. Then let it go 4-6 months beyond when you would normally re-apply. This will allow the extractive bleed at the other end of the application cycle. Yes, it will look a little unsightly, but once seasoned, the timber is a lot less likely to do that again. I’m not saying that it won’t happen. Because it will as that’s the nature of an Australian Hardwood like Spotted Gum. Just that it will be a lot less extreme.
Hi Rohan, I think I’ve made a rookie mistake and over oiled my deck! I used Aussie clear on some some merbau fence panels and achieved a fantastic result but being vertical didn’t need to worry about over oiling. Looks like I got a bit complacent when it came to the merbau deck. It was only oiled 24 hours ago so what is the best course of action to rectify it from here? I’m wondering if a light sand to remove the excess coating then re oiling paying more attention to not over oiling? Thanks.
There are two things to do here to resolve your problem.
1/ Leave your deck as is for 12 months or even longer. Yes it will look patchy and uneven. BUT it won’t do the timber any harm. Then to prep use Grey Deck Cleaner and maybe a light sand of areas where the film still remains before using the cleaner. Then re-apply once dry.
2/ Light sand now – just enough to remove the film only. Use an 80 or 100 grit sandpaper. Then if you want to oil it, one very light coat. I would also note that this applicaiton might only last you 6-7 months. especially if the deck wasn’t weathered first.
The beuaty of a traditional decking oil is that they’re also very forgiving. It’s not a train wreck if you have not followed instructions or you’ve gotten busy and the deck has weathered grey. It can be brought back simply and wihtout sanding in most instances.
Thanks Rohan, will give a light sand now a go. The deck is a couple of years old and had been previously stained with aquadeck. The aquadeck was still in good condition so no issues with greying. I did a thorough sand first with 40 grit, deck washed then pressure washed that of a finally a very light sand with 80 grit but but it doesn’t seem to have taken the oil up like my fence which was new but had weathered about 3 months. Appreciate the advice.
Hi, I’ve just had Merbau decking installed, it’s undercover ,roughly 4.7m x 3m in size, I’ve hosed it down and need to remove a few paint stains.
It was installment abotu 2 months ago but was under a tarpaulin for most of the time whilst other renovations continued, so it’s been completely open to the elements for about 2 weeks, some gets sun every day, another part is always in shade.
What should I be doing to it right now, if anything? As far as i can see, the main 3 things i can do is seal, stain and oil, which should I be doing and when?
Hi Chris, I would keep hosing it down for a bit longer. Merbau is very reasinous and it can take up to 12 months before the “extractives” all bleed out.
Then I recommend you prepare the deck with Grey Deck Cleaner, even though it won’t have gone grey. Then oil it with Aussie Clear and make sure you don’t over oil it as mentioned here. Then you can sit back and enjoy your new deck.
Hi, I’m building an outdoor table using Merbau which is pre-oiled from Bunnings. Do I still weather it for 8 weeks and if so will it bleed out and stain the concrete it’s on? Cheers John
Hi Rohan and have enjoyed reading your responses to the Merbau questions – very informative.
I have some too and hopefully you can help with answers and put my mind to rest – once and for all 🙂
I too am about to lay down some (140mm x 19) Merbau decking (4mt x 4.7mt) under a pergola which is quite protective from rain (except a very small area that may get wet depending on rain direction).
1) Bunnings SA, sell pre-oiled Kiln Dried Merbau. The Merbau leaflet warn about it bleeding, but states the pre-oil helps reduce the bleeding …. I presume not enough though.
Bunnings staff (after coming back from a conference and was told by Merbau reps) I should still wash it down, let it dry, wash again, dry etc. until wash down becomes clear.
— My problem with the wash down and tannin bleed, is I have a very small area comprised of either concrete, Yank gravel stone or lawn.
Are you aware if Tannis would effect the lawn?
2) You have a number of times about weathering the Merbau.
I can’t really leave the number of decking boards I will need out on the lawn for 6-8 weeks to ‘weather’.
Could I …. a) wash them down etc. a few times, oil all sides with your product and then lay the boards down
b) wash them down a few times etc. (do not oil them), lay the boards down and let them ‘weather’ (if needed) under the pergola (1/3 of boards will get very late afternoon Summer sun – remaining 2/3 wont see the sun).
Or other suggestions/advice.
Sorry for such a long story – just trying to explain it all 🙂
No problem at all.
1/ Many timber vendors provide pre-oiled timber these days. Like everything, it has it strengths and weaknesses.
As mentioned by the staff, the weakness is that it will slow down the “extractives” bleed from Merbau. The main strength is, that if the timber is installed in the heat of summer, it will slow the rate of drying down extensively. This will significantly reduce dimensional stability issues like splitting, and warping. Given that it’s finally turned hot for summer in Oz, that’s a good thing.
In terms of the extractives on the lawn, that is the least of your concern. The lawn will be fine. The extractives will stain the concrete and the gravel which will dissapear over time. A bit of sugar soap and a scrubbing brush will remove most of it from the concrete if you’re concerned.
2/ Weather the boards naturally in situ, meaning after the deck is installed. If you have pre-oiled timber, I would allow it to weather for a lot longer than 6-8 weeks. If it were my deck, and it’s under a pergola, I would be looking at 6 months or more. While it weathers, I would be getting the hose on it often to bleed out those extractives. Then I would use Grey Deck Cleaner to prep the timber prior to oiling with Aussie Clear.
If it’s not pre-oiled, then oil it after 6-8 weeks of weathering and washing. As Preschem usually recommends.
And don’t overoil your deck. The film that forms is not durable and is easily scuffed. I won’t tell you that I overoiled my Ironbark deck 2 weeks ago. Because I was in a rush and didn’t take enough care to wipe off the esceess. That’s OK. The deck is looking great (for now as the film is not scuffed) and the deck still looks new, 9 1/2 years after it was installed.
Thank you Rohan for your reply and great advice.
Sounds like I’ll lay the decking – not add further oil – and wait 8 weeks + (even 6 mths as you say) and allow it to “weather”…… and presumably not put any furniture on the decking due to maybe leaching tannins into furniture legs.
Defiantly wont over oil the deck – and I didn’t hear you mention you over oiled your Ironbark lol
Again, thank you very much for your reply as much appreciated 🙂