# Forum Home Renovation Decking  NEW Merbau Decking Preparation

## Harrod

Hi All, 
I am new and I know that so much has been written about this topic but even after ploughing through this great site I am a bit confused. 
Just to confirm:
I have a new saltwater pool and merbau decking to install. 
What I was planning according to advise read is: 
Should I wash the new decking boards 3 times with Napisan PRIOR to installing them?  Followed by deck cleaner? 
Once they are installed, OIL them?  (AND WITH WHAT?) 
Or, am I better off letting them bleed naturally. 
I would rather not do that if possible because I am worried about ruining the pool liner. 
Thanks very much  :Smilie:

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## FletcherP

Hi Harrod, 
It's quite possible that you'll get a number of different answers to this question. FWIW, my opinion follows: 
If it new Merbau, then it shouldn't need any cleaning with Napisan (or Sodium Percarbonate). I know there is a strong fan base here for Napisan, and for aged, stained, mouldy timber, it will certainly clean it up. For new timber, the biggest issue will be tannin, particularly Merbau, and the best way to counter this is to let the timber weather for 6 to 10 weeks. You can do this by laying all your timber out, or more practical, build the deck and let it weather in situ. 
One advantage of letting weather before building the deck is that you can then prep and coat the entire board, however if you won't see the underside of the deck, this is less of an issue. 
Once the timber has weathered, clean it with oxalic acid. Even if you do choose to go the Napisan route, do the last clean with Oxalic acid. Ideally, use a pressure washer before and after - follow the instructions for the rest. 
As to what oil is best, all I am going to add is, unless you really like (and I mean really like) oiling the deck, use a water based decking oil. Solvent based oils look fantastic immediately after doing the job, but just don't last - a bit like water on a sponge. Water based decking oils will last at least 2 - 3 times longer. 
If it is new timber, don't bother with a Merbau tinted oil - Natural tint will bring out the colour just fine - and if not, you can always go darker next time.  
Avoid staining. Although it will last longer, it doesn't do a rich timber like Merbau the same justice as an oil. 
Finally, if it is to be poolside, then 3 coats minimum, and you may want to consider an anti-slip additive to give some grip in the wet areas. 
As to what brand, like most things in life, you get what you pay for. Formulated for the Australian market helps performance. 
Cheers
Fletch

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## jimj

As Fletch said ,there are a number of ideas,suggestions,opinions etc. If I was building a deck of mebau-kwila or any other hardwoodI would forgo the weathering process.  As soon as it is built and all work has been completed I would sand it off quickly at 80 grit and coat it .
I have worked on 10 year old and older merbau decks and can still have the tanins released when raw & wet. The problem with weathering is that it is a very easy statement to make but difficult to define. I have contacted several of the coating manufacturers to seek their definition of weathering. I general comment is" rain & sun over 3 weeks to 6 months". OK but what about the deck under a roofline. " you will need to hose it down several times a week" IMO, hardly weathering 
What I have seen when visiting NEW decks left to weather is generally a trashed deck. Uncoated timber is extremely easy to stain with so many things ie BBQ grease,bird droppings,wine,pet stains and a myriad of other things. Most people will find it very difficult to just stay off the deck while the weathering process is occurring.
I have learned that the secret to having the best possible look after coating is to start with timber that looks stunning with only water on it . The brighter the timber is at this starting point the better the final look after coating. I can see that the day after I sand a board that it is getting slightly darker by the next day.
I realise that oxalic acid is used to try and brighten timber and it does to a certain degree. It won't,  however take out all of the stains,dirt,water marks like a quick 80 grit sand.
Most people are frightened of sanding as they think it is too hard,too long,too dusty etc. 
This sanding is light weight going on new timber. A halfway decent 100-150 mm orbital with good abrasives hooked up to a cheap vacuum will suffice.
Yes it will take a little effort but not the amount of effort required to build.  I can hand sand a deck faster or in around the same time as pressure washing. 
When you think that a piece of timber has been milled,transported and built this is an easy way to brighten it up,remove the surface grime and mill glaze. You can see the wood brighten instantly. 
 After sanding ,blow off excess dust  and vacuum if you want & go straight to coating.
This idea of tanins coming to the surface  under coatings is not something that I am seeing or encountering or getting calls about. I probably see on average some 5 different decks a week built from all available decking timbers and mainly coated in both Sikkens Cetol deck& HLS, All  4 of the Intergrains, Cabots,Feast Watsons and another 5 or so products. 
The only thing that makes this sanding more problematic is the use of domeheaded twist nails. My answer to that is" Don't use them "stick to countersunk ( not flush) SS decking scews. 
Need to stop now as I can feel a another rant building and its too nice a day to have a brain explosion - melt down 
jimj   www.restore-a-deck.com.au

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## Harrod

Thankyou so much Jim and Fletch.   
Jim, we have purchased Marine Grade SS countersunk screws, so I will go with your advice on sanding. 
If you had the choice, what would you coat with?  I'm sure like with everything, each product has its pros and cons.  I am not too worried about how long something will last, I am prepared to re-coat every 6 months if need be.  Am more concerned with quality and what will look good and won't flake etc.  The deck won't be covered at all.  This is my first experience with timber so I really don't have any idea.  Also, each time I re-coat, do I just clean and coat or is it necessary to sand? 
Cheers,
Harrod

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## jimj

Harrod, 
Great to hear the screws are going to be used. just visited a deck this morning. SS phillips head most of which were proud above the surface. It takes so lyttle effort to have them initialy countersunk and the benefit will be later in years when and if the deck ever needs sanding. 
As for which product to use they all have their pros&cons,supporters ,nonbelievers & wouldn't touch with a 10ft pole. 
IMO there is no one best product. 
It comes down to the se and more values, appearance,longevity in the sun,ease of use,recoat time,smell,touch dry time, will it ever flake,crack,peel,delaminate,blister. Ease of clean up turps vs water.
 You can put all of the products pretty well into 2 camps. water based or oil. 
Now water doesn't vary much from 2 molecules of hydrogen and 1 of oxygen but oil can be 60% kerosine, whitespirits,tung,linseed,sheep lanolin.
and a few others .
I read a label the other day on a feast & watson traditional decking oil that states on the ron to the can that it penetrates,protects and nourishes. 
Well it might protect,it might penetrate very little but I can't get ny head around trying to nourish a dead plant which is what a decking timber is.  
IMO the companies play alot on our emotions using words that can lead us into some warm & fuzzy feeling. I have found that any oil derived from a plant or animal is what the mould tends to feed on.  
I have stuck with a water based acyrlic as it has not been letting me down and embaressing me. It touch dries quickly,virtually no smell, has very good sun longevity,very easy to use if you follow some simple guidelines.  I read from others that the con of water based is that if you let them go you may need to resand. Yes you will but at the same time if you do the same with most other products whether oil or water the same applies. Sikkens is an oil that creates a film will crack & peel in the sun. I think it is a better looking  product than the one I use but doesn't handle the sun as well and is more of a hassle to use & deal with. 
I have coated over 200 decks with flood spa& deck because it seems to be keeping my customers for most of the time happy and if they are happy so am I when I come home each day to talk to the beer fridge. 
Good luck 
jimj

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## strangerep

Harrod, 
Before you decide on your finish, read through a lot more of the older threads here that mention Cutek, so that you can get a balanced picture of all the pros and cons. Cutek is a decking oil, but should _not_ be lumped into the same category as most other decking oils like Cabots and Feast-Watson. 
It has the "downside" that you need to wait a week between coats (actually I prefer to wait 3 weeks). It's also harder to get (probably not available in your local hardware store), and more expensive than other oils (but it lasts longer, so I'm ok with that). 
I can also tell you maintenance of an oil-type coating need not require sanding or pressure washing if you're ok with using strong Napisan, chlorine, and oxalic acid sequentially.

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## Harrod

Thanks for everyone's advice.  Jim, I am pretty decided about going with the Spa n deck. 
So, you feel I should just build the deck first and do nothing to the boards prior to install?  I am quite happy to wash them first with nappisan, before I build if you think that would help at all. 
Then I was going to install, give a light sand and coat straight away with 3 or 4 coats. 
Do I just leave the initial 2 steps advised by Flood?  ie. the Powerlift and Woodprep steps? 
God I'll be glad when this deck is done.............. so many decisions and conflicting advice! 
cheers,
Harrod :Annoyed:

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## johnstonfencing

The sanding will do the same thing the powerlift would normally do.  I would still buy and use the wood prep, although not really necessary it is required for coverage under their 2 year guarantee.  It only costs $15-20 for a one litre bottle so for peace of mind I would do it in the unlikely event you need to make a claim. 
Cheers

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## Harrod

Thanks for that, I will buy the woodprep too.

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