How to paint over pre-oiled Merbau decking boards?

[Brian101]

Hi, I have pre-oiled merbau boards just installed as slats on a vertical screening wall. I would like to paint them the same colour as my house (barrister white). What is the best process for me to follow? Thanks

[MitchellMc]

Welcome to the Bunnings Workshop community @Brian101. It's sensational to have you join us, and many thanks for your question about painting a deck.

With Merbau, it's important to strip all tannins and oils out of it before painting. If this process is not completed sufficiently, the timber colour will bleed through your paint, and this is especially prevalent with lighter colours. I'd recommend you use Cabot's New Timber Prep and do several applications of it. This product will assist in removing tannins and oils, but you must cover any hard surface beneath the screening to avoid stains. The runoff will stain hard surfaces and is not easy or, in some cases, possible to remove. Once the timber is finished expelling the red tannins, determined by running water over it and no red colourant leeching, you must wait for it to dry out completely before using an oil-based undercoat.

Please let me know if you have any questions.

Mitchell
 

[Brian101]

Thanks Michell - I will try that

[MitchellMc]

Keep us updated, @Brian101, and please reach out again if you get stuck.

Mitchell

[Brian101]

Hi Michell,

I have applied several application so the Cabots new timber prep and washed multiple times. There is still a very slight colour coming out - noticeable after the rain we are having. Does it need to be 100% clear before applying the paint undercoat? 

I thought also of applying a few coats of the undercoat to ensure blocking.

Thanks,

Brian

[MitchellMc]

It doesn't need to be 100% clear, but you must try to get out as much as possible @Brian101. I'd be inclined to continue the process by flushing it with water twice daily until it runs clear. Applying a couple of coats of the undercoat will certainly block just about all the residual tannins and colouring; it's just best to start with timber that isn't actively leeching colour.

Mitchell

[Perrykay]

I wish I'd read this before undercoating and painting. If I just leave it alone, will the oil leach out ? Any suggestions?

Thanks Kay 

[JacobZ]

Hi @Perrykay,

Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Unfortunately, you will likely experience some issues if the tannins have not leeched from the Merbau. Over time, stains will begin to show through the paint.

To fix this, you will need to strip the timber back using a paint stripper and a paint scraper. Apply the paint stripper following the manufacturer's advice for coverage. Ensure you wear gloves and a mask and carry out the paint stripping in a well-ventilated area.

You might like to check out How To Remove Paint for some guidance.

Once you are back to bare timber, you can use Cabot's New Timber Prep to remove the tannins from the Merbau. 

Once the tannins have been removed, you can undercoat and repaint the timber following @MitchellMc's advice above.

Let me know if you have any further questions.

Jacob