How to remove black marks on new Merbau deck?

[Maursby57]

We just installed a brand new merbau deck. We cut colourbond sheeting on the deck and didn’t notice the metallic dust left behind.  It rained overnight and the dust has left black marks all over the deck. Deck Clean and pressure wash have made no difference.  Can someone tell us how to fix this please?

[Bandicoot]

Had the same problem using an angle grinder too close to a window; hot dust fused to the glass and then started to rust.  I had surprisingly good result just applying rust converter and washing off, but no idea what effect that may have on your merbau.  Perhaps check on an offcut before trying it on your deck, otherwise a sander might be needed.

[Maursby57]

Thanks Bandicoot will try the rust converter.  We have some off cuts we can test.

[EricL]

Hello @Maursby57 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about removing the black marks on your deck.

It's great that you've received good advice from @Bandicoot. I suggest having a quick look at this discussion - How to remove mould and black stains on Merbau deck? by @RMacalintal. The Cabot's Deck Clean and the Cabot's New Timber Prep were suggested in the discussion as possible cleaners. However, I would like to propose using standard detergent and water on the deck first to see if you can wash off the dark rust spots on the deck. If the results are not satisfactory, then you can use the Cabot's products.

If you have any other questions we can help with, please let us know.

Eric

[Maursby57]

Hi Eric, we already tried Cabot’s Deck Clean and it didn’t help. Went to Bunnings today and the staff at the paint aisle recommended Digger rust and stain remover. Will let you know how it goes.

regards,

Maureen

[EricL]

Hi @Maursby57 

Please keep us uprated with your progress, we look forward to seeing your decking panels free of the black marks. 

Eric

[Maursby57]

Hi Eric,

we cleaned the deck with Diggers Rust and Stain remover as per the instructions then we pressure washed. This stuff is magic!  We thoroughly recommend and it was on $32.95 and we only used about 2 cups. 

We have put one coat of Aquadeck Merbau.  It looks amazing! Will be even better when we complete the second.  Thanks everyone.

BeforeAfter

[JacobZ]

Hi @Maursby57,

Thank you for sharing the update. 

The deck looks magnificent after a good clean and some Cabots Aquadeck. I'm sure you'll spend some wonderful time on the deck over the coming warmer months.

Jacob

[John55]

Thanks for posting this, it’s been a lifesaver for me. Same problem but on a new spotted gum deck.

One extra I would add - I started scrubbing but noticed the rust remover itself was enough. So just used a cloth to wipe it on after that. All gone and more gentle. I think even spreading with a mop would work.

[Jason]

Glad it was helpful @John55, and thanks for adding an extra tip.

Welcome to the Bunnings Workshop community. We look forward to reading about your projects and plans for around the house and garden.

Jason