Finished an Exterior Oak Table with Hardwax Oil - Help!

[danieltanner]

Hey all,

I have recently started woodworking (furniture design and making) as a hobbyist and have hit a problem I need some advice on.
I have designed and built a simple table for use in the garden on our outside patio. In looking to finish the table I somehow got confused and added two coats of Hardwax Oil, which I subsequently realised is labelled as “interior use only”.

The table is fabricated largely from Kiln Dried Oak but has some Iroko (breadboard ends), Sapele (low stretcher) and some aesthetic Black Walnut dowels. It is all jointed with Cascamite. A nice tabletop cover is on the way.

Two questions:

• What should I do – any advice?
• What would have been a better finish to use (I have a can of Linseed Oil)?

P.S. Sorry I don’t have better pictures but the table is large (216 x 76 x 80 cm), the garage small and the rain heavy.

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[Sgian Dubh]

Just put it outside and let the weather do a number on it. It'll probably look terrible after a number of weeks, and continue to look terrible for a few weeks or months after that, but once the weather's basically stripped the finish it will start to take on a natural weathered look. In other words, my advice is to make no effort to 'correct' your mistake by trying to strip what's on the table followed by applying a film finish of some sort.

Going down that route means you're committing yourself to regular maintenance work of sanding and reapplying your chosen finish. That's absolutely fine if you know you'll actually make the commitment to doing that maintenance. But a poorly maintained finish looks worse than doing nothing at all and letting the wood age naturally. Not only does it look worse, a damaged film finish leads to faster wood decay than no finish at all because a damaged finish tends to allow water in but then prevents it escaping easily. If there's no finish any water that gets on and into the wood fibres can also escape relatively easily.

As an example, the oak outdoor table below had one coat of linseed oil applied primarily to make the wood look pretty for a photograph. In the second image the table had been left out in all weathers for about six years and photographed again. No work had been done to maintain the original finish. It took about 9 - 12 months for the table to develop the greyish patina, in this case with evidence of algae or moss getting a foothold which can be taken care of with plenty of water and stiff brush every now and then. The no-finish approach is the one I favour. Others may disagree with that preference. Slainte.

 

[Istrickl]

Not sure if it'd work but treatex do an exterior oil that's uv resistant.i wonder of a coat or two over the existing would help. Treatex are based in Thame and have always been very helpful, I'd suggest a call would be a good start.

Cheers

 

[Doug71]

I would say keep the table indoors, it's far too nice to be an outside table!

A couple of years ago a house in our village had a nice large pair of Oak driveway gates plus pedestrian gate fitted. It looked like the gates were kiln dried Oak and the posts air dried, the gates were finished with some kind of oil but the posts were untreated. After about a year all the horizontal surfaces on the gates were black, the vertical surfaces still looked bright and the posts were going grey, now another year on the gates are all black and look terrible while the posts are a lovely silver grey colour. It looks like the oil has caused some kind of mould to form, this may eventually go away but I bet they wish they had left the gates untreated.

I can understand why for something like your table you would want to go for the clean look to show off the wood but as said with oils you must keep on top of it.

 

[johnnyb]

The only longish term clear finish is boat style. So clear penetrating epoxy sealer then le tonk/epifanes yacht varnish(coat after coat). Expensive though beautiful. No idea how it would work with oak though.

 

[Sgian Dubh]

It looks like the oil has caused some kind of mould to form, this may eventually go away but I bet they wish they had left the gates untreated.

I believe that's what happens, the oil encourages mould. I've seen that effect many times. It happened with the table I showed earlier which was photographed after a single coat of linseed oil. But for needing to take a photograph with the wood looking attractive I wouldn't have bothered applying the oil for exactly the reason you mentioned, i.e., unattractive short term blackness. It took about twelve or fourteen months for all the horizontal black surfaces to fade away to be replaced by grey. Having said that, the table's surface is quite rough most of the time with raised grain caused by regular wetting.

If the table's needed for eating off I can, if I feel like it, get some 80 grit abrasive and give it a quick sand down. Every now and then, as I mentioned in my earlier post, I go at it with hot water with maybe a bit of bleach added, and a collection of stiff brush, wire brush, a scraper, and a sheet or two of coarse abrasive paper to knock off the fuzz after the surface has dried: I'm not very fussy about caring for it, it being pretty robust and utilitarian. The table's about thirteen years old now, and was made from odds and ends of mostly European oak, some air dried and some kiln that table before I have to replace it. Slainte.

 

[PerryGunn]

I used the clear version of Barrettine 'Nourish & Protect' Wood Preserver on my large gates and it seems to have worked fine - leaves a nice natural finish, there's been no mould/fungus or weird discolouration and the gates have gradually silvered. I reapply every couple of years (if I remember and I get a nice dry weekend)

https://www.amazon.co.uk/gp/product/B0711BG3XR