Finishing oak bench for outside use

[AES]

Dear all, any advice on the following points would be much appreciated. Please note that I’m very much a beginner when it comes to finishing “real wood”.

Last year my better half wanted a garden bench. As I had little time to spare (my excuse & I'm sticking to it!) I bought a cheapo unit from one of our DIY emporium in the knowledge that I would have to "do something with it" after a short while. On the up side, it did feature what we felt were rather nice cast metal legs and back rest. Anyway .....

.... just as expected, & after less than 1 year (and that did NOT include being left outside during the winter, see below) the approx 18 mm thick oak slats are showing signs of considerable distress (plus poor original machining!), AND with quite nasty-looking black marks where the oak slats contact the metal parts.

I have now invested in some 10+ year old locally-grown & very well seasoned oak which is 25 mm thick. I intend to replace all the existing wooden parts (Chinese oak?) with this local oak. My questions concern both finishing and (if possible) protection against black marks arising from contact with the metal parts and nuts & bolts.

Please note that ideally it will stand outside all the time (unless absolutely necessary I would rather not dismantle it every winter). Typical weather conditions here range from about a foot of standing snow and minus 15 degrees C overnight for around a couple of months each year up to temperatures of 30+ degrees C in summer; and rain is not exactly unknown here! :lol: But I could think about making some sort of waterproof cover for use full time during the cold & snowy winter months.

So my questions are:

1. Should I make felt, soft plastic, or rubber “gaskets” to be placed between the oak and the metal contact points? And if yes, what about the holes where the (plated) bolts pass through the wood?

2. Or any other suggestions for protecting against black marks?

3. After a little light staining (to get a similar colour overall) should I finish the oak with oil (for outside furniture)?; or varnish?; or nothing at all?; or something else?
(I have light overall sanding then 2 coats of single part polyurethane varnish in mind, but as above, having no experience I’m fully open to better suggestions).

Just to make your task a little more difficult I should point out that I do not often see the trade/brand names that are often mentioned on this Forum in the shops here in Switzerland. So please suggest the best TYPE of finish rather than a specific brand name; also please outline the necessary preparation steps for the finish suggested.

Thank you all in advance.

Krgds
AES

 

[Harbo]

I use UV protection oil on my English oak garden furniture, which has been left outside for over 5 yrs now.
Still going strong - the one completely exposed has gone silver grey but still "waterproof" the other, which I keep under wraps still has it's original colour.

Rod

 

[AES]

@Harbo/Rob,

Thanks very much for the prompt reply. I must say the dark brown bench looks in brilliant nick for something that's been outside for 5 years. But for "our" taste (i.e. 'er indoors), it's a bit dark. The single seat lounger is more the sort of colour we're aiming for though I'm a bit concerned when you mention the silver-grey weathering - we see a lot of that weathering around here (and on "Grand Designs") but neither of us like it all that much - we prefer the "pristine, just finished" look.

Anyway, a couple of questions if I may re the UV-resisting oil you mention:

1. I guess you just sand the raw wood in reducing grades - say 120/400/600 - before applying (in our case) a little light stain, then apply the oil over the (dried) stain, correct?

2. How do you apply the oil please - brush, spray, or cloth pad?

3. How long does the oil take to dry/what are the chances that someone (wearing a white skirt, naturally!) will pick up some of the oil please?

4. How often do you re-do oil the furniture (assuming a covering of some sort over the winter)?

And a supplementary if I may:

As per my OP, is there any point in me making up plastic/rubber/felt "gaskets" for the points where the bolts go through the wood & where the wood touches the metal arms and backrest (to try and stop the black staining)?

Thanks a lot

Krgds
AES

 

[Harbo]

I forgot to say that the grey bench was originally coated with Liberon Garden Furniture Oil but it went grey.
I've since used OSMO UV protection oil which has prevented the newer lounger from going grey and on the bench
As a coating it seems to offer better protection?
I apply it with a brush and rags - I did it about two yrs ago - it probably won't be done this year as it seems well protected?
I would think this oil, when dry, should prevent the metal blackening?
The grey bench is not covered but the lounger is ( but still left outside).
The lounger has brass fittings and the bench SS fixings so I don't have the metal staining issue.

Bench when first constructed.

Rod

 

[yetloh]

I wouldn't bet on the oil preventing staining for long, bearing in mind how open grained oak is. Is there a poassibility that you could put some sort of barrier between the oak and the iron frame?

Jim

 

[Matt@]

re. the staining from the fittings, cant you replace them with fittings other than steel?

 

[paulm]

It's the nature of oak to turn silvery grey with age, and to stain black if in contact with iron.

My thoughts would be to recognise that and not fight it, or go for a different material, maybe western red cedar or iroko if wood, or plastic resin if not :shock: :lol:

It's a losing battle to use oak, local or not, and then try to make it not behave like oak, although Rod's lovely work maybe proves me wrong to some degree !

Outdoors is outdoors, don't think it should be expected to accomodate white skirts either, much better to change the skirts or stay indoors ? :lol:

Cheers, Paul

 

[AES]

Gents,

Thanks for all the inputs, very useful. And Harbo/Rob, my apologies, last post I forgot to say how impressed I am with the superb work you did on that furniture - I can only dream of reaching such standards in woodworking.

Here's what I'm going to do:

1. Find UV-resisting oil (I think I can find an OSMO retailer here);

2. Replace the current plated steel nuts, bolts & screws with stainless steel;

3. Make little rubber gaskets to go between the wood and metal contact points;

4. Make a waterproof cover for the winter months.

Thanks again to you all. When it's finished (don't hold your breath) would you like a pic, bearing in mind that as per my original post, it's not exactly "all my own work"?

Krgds
AES