Exterior door

[marcros]

I have a hardwood glazed door which I believe is meranti. I want to use it on a lean-to greenhouse structure. The door will be hung on the solid wall rather than from the greenhouse frame and the greenhouse isn't being used for growing, more as a conservatory so it won't be high humidity and constantly damp.

I don't mind the door going silver as it ages, but is there a finish that will protect it from the weather? I know that meranti isn't the most durable of timbers.

The door was free so whilst not ideal is what I have to work with.

 

[Jacob]

Depends on the detail design a lot but linseed oil paint is your best bet. Or creosote if you don't mind the pong.

 

[marcros]

What about straight linseed oil? I don't really want a colour, a brown for now, fading to a silver is fine.

 

[marcros]

Fairly simple thing. Through tenons. Not much more to say.

 

[Adam W.]

Linseed oil will work ok, but it may go mouldy as the paint has a fungicide in it to stop this.

 

[Doug71]

Are you sure it's solid timber, many are just veneered over laminations and won't last 5 minutes if not well sealed?

Sorry if teaching granny to suck eggs but it's not often obvious unless you look at the top or bottom ends.

 

[marcros]

what about the other oils such as pure tung etc? I dont do much exterior finishing beyond fence painting.

 

[marcros]

Are you sure it's solid timber, many are just veneered over laminations and won't last 5 minutes if not well sealed?

Sorry if teaching granny to suck eggs but it's not often obvious unless you look at the top or bottom ends.

I am 99% sure it is solid. it has the horns still attached on one end and I can see the through tenons. it is half of a pair, so has been rebated- I cant see any sign of veneer.

if I do look at the top and bottom, would it be obvious?

 

[Jacob]

Linseed oil will work ok, but it may go mouldy as the paint has a fungicide in it to stop this.

It will but it will go black slowly, over a few years.

 

[Doug71]

if I do look at the top and bottom, would it be obvious?

Yes, you will be able to tell by the end of the stiles, if it's solid the stile will be one piece of end grain, if veneered it could be several smaller pieces joined or a solid lath that runs right across the bottom/top end and you might only see an edging lath at each side rather than the full end of the stile.

 

[marcros]

Yes, you will be able to tell by the end of the stiles, if it's solid the stile will be one piece of end grain, if veneered it could be several smaller pieces joined or a solid lath that runs right across the bottom/top end and you might only see an edging lath at each side rather than the full end of the stile.

I will have another look but I am 99% sure it is solid.

 

[thetyreman]

le tonkinois is good stuff, expensive though, but I like it for these kinds of jobs.

 

[Adam W.]

It will but it will go black slowly, over a few years.

Depends on the conditions.

The Norwegians did a study on home made linseed oil paint with varying amounts of zinc oxide in it as a fungicide. They found that commercial linseed oil paint had visible mould growth after 13 months, so I imagine that oil on its own would go mouldy quicker than that. Their sample M0 had no zinc oxide and was quite mouldy compared to the rest of their samples. The commercial paint also had a fair amount of mould growth over the same period, but it doesn't say what fungicide was that they contained.

They found that a zinc oxide content between 7%-10% gave the optimum protection, as a ZnO content over 10% tended to be brittle and start flaking off.


Gobakken, Lone & Grodås, Eva & Kolstad, Sigrun. (2014). The effect of zinc oxide (ZnO) in linseed oil paint on growth of blue stain fungi and surface moulds. Agarica. 34.

 

[Jacob]

Depends on the conditions.
...

I meant just oil on its own. Have had several bits of rough out door furniture going black but still staying weather resistant.
I did wonder if the black of 'black and white' of half timbering is a result of straight linseed oil use.

 

[Adam W.]

Their sample M0 was just oil with pigment, so I guess it has a similar resistance to mould growth as neat oil.

 

[Aligish]

For what it's worth...

I tried Tung Oil on a sign I made for a chum eighteen months ago. It's Larch and has been in an exterior, very exposed position and.....


It's still fine. It's in great condition actually - no sign of any weathering at all. A very pleasant surprise.

I know it's Larch but there's no sign of the greying I would have expected - we are on the coast of the North West Highlands so it's taken a fair battering over the Winter.

First experience of Tung Oil and not my last...

 

[nickds1]

I've used tung/Danish oil successfully, but as mentioned in another thread, I'm a big fan of Osmo 420 UV stable oil. Lovely stuff.

 

[Aligish]

Yup.

Me too.

But not Danish oil...