Welcome to the Bunnings Workshop community @michael183. It's a pleasure to have you join us, and many thanks for your question.
Was there a particular product you had in mind? Products like 70mm x 19mm x 1.8m Pre Oiled Merbau Picket Blanks come pre-oiled and, due to the penetrative nature of the oil, it will prevent the effective uptake of paints.
Un-coated Merbau can be painted, but it would be worth either letting it weather naturally or doing a new timber prep on it. It would also be a good idea to use Rust-Oleum Zinsser 3.78L Bulls Eye Primer Undercoat Sealer and Stain Blocker. Merbau has a lot of natural pigments and tannins in it, which will bleed through lighter paint colours if you don't block them.
If you can let us know more specific details on the Merbau you wish to paint, I can provide further instructions on how to go about it.
Please let me know if you have any questions.
I want to seal Maubou timber that has been weathered for almost 8 months.
built a slat fence.
what can I use that would last for at least five years.
Is the 3.78l bulletin eye primer clear coat sealer
Welcome to the Bunnings Workshop community @Pooban. It's sensational to have you join us, and many thanks for your question about painting Merbau.
Rust-Oleum Zinsser 3.78L Bulls Eye Primer Undercoat Sealer and Stain Blocker is an undercoat that will go onto the timber before your topcoat paint. If your timber has weathered and you are painting in a darker colour and not a shade of white, then you'd likely not require the undercoat. An exterior self-priming paint like Dulux Weathersheild would be suitable for your project and last much longer than five years.
If this is a larger fence, then I'd higher recommend you consider purchasing a spray gun. Not only will it be faster than applying the paint by hand, but you'll get superb results. Check out this helpful step-by-step guide: How to spray paint a fence.
Please let me know if you have further questions.