sealing merbau

**Stan 101** · 14th September 2009, 04:11 PM

Hi all,

I just received my entrance door from the joinery department. They recommend I seal the merbau straight away with Sikkens or similar before it starts to leach. They over emphasise the sealing under the door sill before installation.

I wander down to the paint shop today to get the Sikkens and the guy really tried to persuade me from sealing the merbau for 6 months to give it time to bleed.

The door and frame will be exposed to the elements so I need to do something. My options are:

1. Don't seal it before installation and have my warranty void, have the merbau bleed all over my colourbond cladding below, and worry that I'll never get a chance to seal under my sill once installed.

2. Seal the joinery before installation to keep my warranty intact and face the unknown concequences of a sealed (timebomb????) merbau just waiting to bleed out.

I would have thought that by sealing the timber before it gets wet would lock up any chance of it bleeding out. If it was a deck I wouldn't be concerned but it not and this door cost me a lot of money and pain and suffering so I want it right.

Please guys any suggestions or experience here? I really need to get this door installed soon.

Also, the joinery people do not recommend water based acrylic sealers. The people at all three paint places I went to all recommended water based as it doesn't yellow but they were also the ones who insisted on not sealing the timber at all before installation.

cheers,

**spectre** · 14th September 2009, 08:37 PM

Ok, lots of issues...

New Merbau is chock full of tannin and oils, this makes coating it problematic. Left to its own devices it will leech these extractives and dry out over a period of time leaving you an essentially inert surface that coatings will stick to. If you try and coat it prior to this process, the usual accepted theory is that they will still try to leech out pushing your coating off the surface at the same time.

The extractives are mostly water born, so coating with a waterbased coating is more problematic because they will was into the surface contaminating your coating. Also all acrylic coatings are more moisture peremable than oil based coatings. So if the surface comes under duress, then you will get waterstaining and mositure penetration into the timber.

Oil based coatings on the other hand tend to have better adhesion to these types of problematic timbers, quite often any of these types of hardwoods even if painted rather than cleared perform best if primed/undercoated with an oil based product prior to finishing with an acrylic.

Usually most coatings manufactureres will have some sort of cleaner they will reccommend you use prior to finishing merbau, all those different deck cleaners out there

Mostly work the same way, a blend of sugar soap, and oxalic acid in an effort to remove the surface oils/tannins and brighten the surface. Even sikkens have recommended this in the past or leaving it 6-8 weeks to weather in, never come across 6 months before, it'd be grey by then.

In short... I'd probably in the middle somewhere, coating new merbau can be problematic, I'd also still lean towards the sikkens its a good product gives a nice finish and oil based products are more forgiving than water based products. If the unit is not installed yet, I'd probably still be inclined to was it down with a timber cleaner though too. Or maybe at least metho to help settle that surface down a bit.

Just bang on 3 coats of cetol HLS 077 (Natural) jobs done.

Regards

**Stan 101** · 15th September 2009, 05:42 PM

cheers, I will use the sikkens...

Thanks for the reply.

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