How to maintain Merbau deck?

[smhasnain]

 

 

 

 

 

Hi

I replaced my 23-year-old, 12m deck with new marabou slates in June 2023, and then in October 2023, I treated them with Cabots Merbau Aquadeck Exterior Decking oil. Throughout the process, I was continuously getting advice from the experts at Bunnings.

Now, I feel it’s time to give the deck a bit of a refresh, especially since the heavy traffic areas have gotten quite dirty. I’ve attached some current photos for you to take a look at. Could you please let me know what steps I should take now and what materials would be best to make the deck look brilliant again?

Thanks so much!

Syed

[smhasnain]

Thanks Eric for your prompt reply. I will wait for Dave and Nailbag’s recommendations before taking further steps. 
Just for the sake of curiosity, if i opt to put another coat, Will i need to wait for warm sunny weather in Melbourne?. 

Thanks. 

[EricL]

Hello @smhasnain 

It's best to apply the next coat in the morning when its not too hot and there is no sign of rain for the next few days. I don't recommend coating the decking surface when its too hot or when its in direct sunlight. 

If you need further assistance, please let me know.

Eric

[Dave-1]

Good Evening @smhasnain 

Do you have any pics of the deck after you sanded it? I am just wondering why that darker area is on the steps. I think it has come up nicely and as @EricL has suggested another coat will belnd it more so (it will also darken it)

I would dispose of the old oil you have been asking about as @MitchellMc has said the materials would have seperated and hanging out on the bottom of the can Never worth using something after going to the effort to sand a deck.

I am a little confused as to the grit of the sandpaper you have used tho, I used a belt sander with a brit of 36 to sand back my deck.

Hardwood deck restoration Step 2 will show the sandpaper I used.

Dave

[Nailbag]

Hi @smhasnain 

I suspect the issue causing your unhappiness is probably in the areas where the more weather blackness thats was deep in the boards grain. Your choices here are:

1. Sand those specific boards much deeper back to raw merbau to remove the blackness. Boards in this bad of condition I always start with 180G then move to 240G.  But this would be very labour intensive and replacing the few worst ones would be a consideration. However it will take several coats of oil on just those boards to match them back with the rest colour shade wise..

2. A similar suggestion to @EricL but only apply oil with a brush to the non-blackened boards first to darken them. This will help blend all the boards to the same colour. When I repair badly weathered decks I use this approach, but then apply another coat over the the top to even them out. In some cases the final top coat would be a clear so not to darken the boards further.

Bottom line is that this shows the importance of regular oiling and not letting the boards get to a state where the old has faded to grey. Once you get this lot sorted, make a note to give 1-2 fresh coats at the start of every summer. 

Nailbag

[Jacob-Hawkins]

Hi Syed,

I've come across this exact situation many times. Water-based stains (like all coatings) wear off unevenly — partly due to UV, but mostly from foot traffic, as you noted. The results you've achieved are about as good as you can get without fully sanding everything back and starting fresh.

The water-based product forms a semi-transparent film on the surface. When some areas still have it intact and others are worn off, applying more just stacks the coating unevenly — creating a patchy look with darker, heavier sections where it's layered.

As others have said, adding more coats can help make it look more uniform, but it will also make the timber darker, more opaque, and hide more of the grain. That’s the cheapest and easiest option.

If you want to get the original look back, I’d recommend sanding it all back. Grab a belt sander with 36- and 80-grit belts. Start with the 36 to quickly remove the coating and blackness, then switch to 80. Finish off with an orbital sander using 80 or 120 grit (depending on the coating you're planning to apply).

In future, try to recoat just as the original layer begins to fail — usually at the first sign of patchiness. That way, you’ll maintain the colour and consistency without needing to start from scratch. Depending on UV exposure and wear, you might get several seasons before needing a full restoration.

P.S. Belt sanders have the added benefit of making your arms slightly longer!

Let me know if I can clarify anything.
Cheers, Jacob 

Before Sanding - Worn from UV & Foot TrafficAfter Sanding - Ready for any coating

[JacobZ]

Hi @Jacob-Hawkins,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

I trust Syed (@smhasnain) and our other readers will appreciate the fantastic advice you have offered.

Thank you for sharing your knowledge.

Jacob