Oiling outside furniture

[Deadeye]

I think it's fair to say that I'm a complete noob at finishing anything for the outdoors.
I made a nice garden bench (oak) and put 2 coats of OSMO UV on it. One winter later it is a horrible blotched mess of slightly golden oiled areas and blackened patches that look like mould but aren't dusty, just very discoloured.
What did I do wrong? Can I retrieve it?

 

[HOJ]

What did I do wrong?

Answer already in the question.

You

put 2 coats of OSMO UV on it

I make Oak benches and never offer to apply anything to them, knowing full well it will become someones life's work to maintain it.

 

[eribaMotters]

Git it a very light jet wash to try and remove or at least break the surface finish and then let nature do it's job. It will eventually turn a lovely pale grey. Do not apply anything again, just a bleach wash or light jet wash if you really have to every year.

Colin

 

[Jacob]

Linseed oil paint is good. I've got bench and handrails outside which get a splash of paint every year or two.

 

[Deadeye]

Answer already in the question.

You

I make Oak benches and never offer to apply anything to them, knowing full well it will become someones life's work to maintain it.

Lol. "I wouldn't start from here" was also already in my opening post. Given that I am starting from here do you have any wisdom either more useful or more amusing?

 

[Deadeye]

Git it a very light jet wash to try and remove or at least break the surface finish and then let nature do it's job. It will eventually turn a lovely pale grey. Do not apply anything again, just a bleach wash or light jet wash if you really have to every year.

Colin

Thanks colin
Worth sanding to help that along do you think?

 

[eribaMotters]

Thanks colin
Worth sanding to help that along do you think?

A light rub over with 120 wouldn't harm, your just trying to break the surface so the elements can get under the finish. It will probably look worse before it gets better.

Colin

 

[HOJ]

do you have any wisdom either more useful or more amusing?

Can't do amusing, lets try wisdom, I would be very hesitant to even go near it with a pressure washer, seen it done, raises the grain terribly, and I doubt it'll shift off the oil that has adhered and which has not been affected by UV.

Sanding, you'll probably need to start at 80 grit and maybe lower, or just leave it to the elements.

 

[Deadeye]

So my takeaway is that despite glowing support on here; OSMO is really an interior only product.
I've used it indoors and been really impressed; but it's been absolutely a crock of manure outdoors (despite being lovingly applied exactly per instructions)
I've also made 6 chairs that have gone the same way, so I'm going to pressure wash one; sand one at 150; sand one at 80; and see what happens.
Thanks all

 

[Doug71]

The external Osmo stuff seems okay for vertical surfaces but doesn't last on horizontal surfaces.

 

[Deadeye]

The external Osmo stuff seems okay for vertical surfaces but doesn't last on horizontal surfaces.

i.e. useless for furniture

 

[eribaMotters]

Can't do amusing, lets try wisdom, I would be very hesitant to even go near it with a pressure washer, seen it done, raises the grain terribly, and I doubt it'll shift off the oil that has adhered and which has not been affected by UV.

Sanding, you'll probably need to start at 80 grit and maybe lower, or just leave it to the elements.

HOJ, to be fair I did say " a very light jet wash "

Colin

 

[HamsterJam]

i.e. useless for furniture

If I recall correctly, it states on the tin that it’s not suitable for use on horizontal surfaces outdoors.
I have some experience with it outdoors on a vertical surface (summer house) and it was holding up well after two years. We moved house so I don’t know how it’s fairing beyond that.

 

[thetyreman]

pure tung oil is very water resistant, I'd leave oak unfinished and let it grey.

 

[TRITON]

i.e. useless for furniture

It would always have it place on standing furniture that doesn't get touched that often, mantles, display cases etc.

 

[Deadeye]

If I recall correctly, it states on the tin that it’s not suitable for use on horizontal surfaces outdoors.
I have some experience with it outdoors on a vertical surface (summer house) and it was holding up well after two years. We moved house so I don’t know how it’s fairing beyond that.

The verticals (legs,back slats) are just as bad

 

[imageel]

I'd add that both Osmo's longevity and UV resistance is low, this is my front door fabbed out of Sapele10y apart, partially sheltered albeit it does catch the setting sun...