Exterior oak, old

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I have, if I may, registered seeking advice but I do appreciate that a forum would like participation too, so I hope to join in a bit. My skills are limited to rather bodged side-tables and benches, and cheap picture frames out of moulding and pins and glue. It's a while since I made a bench, I'm told one's forbidden to buy used railway sleepers these days.

Anyway, exterior oak. I am newly responsible for a church with original oak entry doors from 1907 and they've not been maintained. The last attempt, maybe twenty years ago, was a coat of brown paint which is now mostly gone, what's left will flake off from being so thin and dry and cracked. I intend scraping it off and lightly sanding and then rubbing white spirit on to get a dust-free surface.

Everything I've seen online has a mantra about boiled linseed - "except exterior oak". Is that because it's too thick to penetrate the fine grain? The three clear protecting treatments I've seen recommended are raw linseed, tung oil and Danish oil (the 50% tung oil one with varnish additives).

I assume I'll have a few dry days before I make a start.

Before then, would anyone like to offer suggestions?

 

[deema]

Traditionally church doors were coated in linsead oil, the advantages are that its a very hard wearing, easy to apply oil, however it has a few disadvantages.

1. It can be slow to dry, you wipe it on, leave for half an hour and then you must wipe off the excess. Repeat after 24hrs unto no more oil seems to be absorbed. It's the same process for all of the oiles you have mentioned. If you don't wipe off the excess linsead you can end up with a nasty sticky mess, that's a nightmare to get off again - it clogs sand paper and needs scrapping off.
2. It does not offer any UV protection so, over the years the door will go grey in colour, the characteristic look of a church door. If you want it to look like newly sanded oak, an OSMO oil for you.

I live in an old Weslian chapel, which now has an oak front door. I've used Tung oil in it. It's easy to use, drys very quickly and is less prone to sticky messes. The process of applying is the same. My door is north facing and has been annually given a light wipe over with Tung oil every year for the last 5 years and still looks as good (nice oak colour) as the day I fitted it.

If you want a more durable UV stabilised finish that looks more like a 'varnished' finish use Osmo Oil. I have made some oak gates for around the house and these have had the OSMO oil treatment. I chose satin Oak OSMO oil and applied two coats with a final top coat of clear OSMO oil. This is more like a paint to apply, simply brush it on, leave 24 hrs, light rub down and repeat. Don't sand to too fine a grit....read the tiin.

The gates originally had a mixture of coatings so that I could see how each faired. A couple had boiled linseed oil, and a couple had Tung Oil. Boiled linseed oil looked good for about 1 season before starting to darken, Tung Oil looked good for about 3 seasons before it started to darken. These were exposed to the sun. They now have been sanded up again and OSMO oil applied. Two seasons and still look perfect.

Buy your oil / finished for a very reputable dealer, and buy a decent brand if buying Tung or Linsead oils. There are some fake tins of stuff out there that you can stung with that can turn your oak pitch black......an experience I've had!

PS don't use Teak oil, it will can turn oak black!!

 

[spot]

Thank you very much deema, that's all stuff I needed to hear. Wiping off wasn't in my mind at all as a priority but I did think I'd check the library for a book before I started.

The oak is currently completely grey and I doubt there's much colour to be found just under the surface. There's a small side door of the same wood, I might start out with that one and perhaps try a tentative corner before getting stuck in.

 

[marcros]

i don't know how deep the greyness will go, but you might be surprised. It is only the stuff that has been hit by UV light that has lost its colour and it can't penetrate below the surface.

I had a grotty old cedar table outside. A quick sanding and a coat of oil and it wasn't grey any longer. Sadly, it was still rotten and fell to bits pretty soon afterwards, but it went looking good.

There is a comparison on the forum about a few different treatments, where somebody tried a few and left them outside for a few years. Worth looking for.

I like oiled oak, I don't really like the ones that have been treated to keep them from fading, but it is a lot less annual maintenance. Osmo do a UV oil, which I used last year. It is too soon to see whether it is effective, but it was part of the comparison test.