finishing live edge spotted gum slab for outdoor vanity

I have a spotted gum slab that I plan to use as a vanity table for a carved out rock basin. It will be outdoors & exposed to all weather. It will be against a brick wall with live edge facing out.
I've levelled & sanded the top (and roughly the bottom). I think I want to leave the live edge fairly natural, ie not sanded back.
What product do you guys recommend to finish it - oil vs varnish? & how to apply it to the rough live edge? Should I finish the underside too?
Thanks in advance. First time I have done anything like this.

Hi Kerrie and welcome to the forums,

Timber outdoors in all weather is a hard ask. Traditionally, timber outdoors was painted with an oil-based enamel paint, and that lasts well. Probably won't need re-painting for over 10 years. Some paint colours can look just like wood - or be wood-grained (search it www) to look like wood. I have been assured by wooden gate makers that one should not use acrylic paints as they hold any water that gets into a joint or crack and help the wood to rot. The oil-based enamels supposedly 'breathe' so that does not happen.

If you want the timber to look like timber then the options I know of are:
Use a clear finish like a marine or decking oil and re-coat frequently;
Use a pigmented outdoor oil (changes the appearance but lasts longer between re-coats);
Use a polyurethane designed for marine use - looks nice and shiny, but when it fails you have to scrape and sand it all off and start again.

I use an oil designed for boats, called Deks Olje, it is available from Whitworths Marine and probably other places. It comes in two types #1 is thin, like water, and you put it on wet-on-wet until the timber will not absorb any more. That gives a matt finish. Deks Olje #2 is thicker and you let it dry between coats, it gives a gloss finish. When it shows signs of deterioration you just paint some more of the #1 over the top until the timber won't take any more. Depending on the weather exposure you will need to re-coat every 3-6 months for full sun or up to 2 years for more protected environments. I have used it on Australian cedar outdoors with good success.

Marine polyurethanes may last a couple of years, but, as above, stripping them off to re-coat is a lot of work.

It is better to coat all surfaces for something out in the weather, i.e. both top and underneath.

David

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Originally Posted by Xanthorrhoeas

It is better to coat all surfaces for something out in the weather, i.e. both top and underneath.

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:yes: ALL surfaces. Including inside the cut-out(s), where the basin/fittings sit.

Ideally, make the cut-outs as large as possible whilst still allowing a good mounting for fittings and without compromising the integrity of the slab, to minimise the area of timber/other object contact. This reduces the area in which moisture can be trapped and gives what does become trapped a better chance to dry out.

(No matter what sealants you may use around the basin edge, they will fail over time. For longevity it's best if you plan ahead for it. ;) )

Welcome Kerri

I'm about to do something similar with a redgum slab for an outdoor shower. I'm probably going to use this for the finish: Norglass Paints and Specialty Finishes: Northane Gloss
It was recommended by someone who does this sort of thing professional.

Anyone else used this marine 2pack poly that can vouch for it?

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Originally Posted by Twist

Anyone else used this marine 2pack poly that can vouch for it?

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Hi Twist. Yes, I have used the Norglass two-pack poly on wooden boats. It looks great (if you want a gloss) and lasts well. But, when it does deteriorate, it is hard work to scrape/burn/sand off and re-finish. Also, with the two-pack and even the single pack polys, if you have a joint, or a scratch or hole, the water gets in a stays three, rotting the wood and making the finish peel away. For a boat that is tored in a shed the two-pack is wonderful as the amount of use a boat gets gives minimal sun exposure (you know how it goes, there are only really two times a boat owner loves a boat - when they buy it and when they manage to sell it as they are usually little-used).

That's why I stick to the marine oil Deks Olje. It doesn't last anywhere near as long (or look as glossy) but wow it is so easy to re-coat.

I would prefer to use oil, but I was told since my slab is going to be used vertical the oil would essentially drain out over time. Do you think this is true? sounds odd to me.

Quote:

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Originally Posted by kerrie_t

I have a spotted gum slab that I plan to use as a vanity table for a carved out rock basin. It will be outdoors & exposed to all weather. It will be against a brick wall with live edge facing out.
I've levelled & sanded the top (and roughly the bottom). I think I want to leave the live edge fairly natural, ie not sanded back.
What product do you guys recommend to finish it - oil vs varnish? & how to apply it to the rough live edge? Should I finish the underside too?
Thanks in advance. First time I have done anything like this.

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I would coat it in decking oil (cabots) at least you can top it up a couple of coats during the first year , cut most of the dap off , it doesn't last long in weather, I just cut 20 mm off parallel to the live edge, follow the shape ...



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I refinished a table and 4 chair set my parents have about 16 years ago with 3 or 4 coats of Wattyl Marine Varnish from Bunnings. It started looking a bit tired about 5 or 6 years ago and the varnish is well and truly in need of repair now. The furniture sits out on a balcony but does get a fair bit of afternoon sun and it does get rained on when it rains hard. I'd say a decade out of the varnish is better than expected, especially since it was my first refinish job. The Dulux metal paint though is still going strong.