Wood Preserver - which?

[skier-hughes]

Not strictly period property, but in a few years time my log cabin may be listed

Would linseed oil be a good product to use on the naked soft wood to preserve it?

I'd use the Holkham variety and am happy with the colour it would end up.

Should I look at products like Cuprinol etc instead?

It wouldn't have any other coating.

Graham

 

[biffvernon]

Linseed oil has no 'preservative' properties in terms of biocidal action.

 

[skier-hughes]

OK, lost me on that one.
Do you mean won't protect against insect/fungus?
Do I need to worry about that?

Graham

 

[biffvernon]

Yes. Linseed oil is nice healthy stuff - you can drink it - or feed it to moulds and bateria as it won't kill them

Best way to preserve wood is to keep it dry. Next best is to build in such away that it does not stay wet when it stops raining and the sun come out.

Fungicides and other poisons should only be used as a last resort when other precautions are not available.

 

[Gervase]

As Biff says, keeping it dry is the best bet. Borax is a good deterrent for both insects and fungus if you're really worried about the building getting attacked (you can buy it in Boots). It doesn't have the vile organophosphates you find in proprietary wood preservatives and is harmless to people and animals, but, being water soluble, it will leach out of the wood gets soaked.
Timber buildings in the past were either left as they were or protected with a dollop of pitch (or, later, creosote or Sadolin).

 

[Andrew Bodenham]

My experience from experiments is that linseed oil on it's own on exterior woodwork is a disaster. Expect it to go black and mouldy within a year, and provide little in the way of meaningful protection. Never again!
As the base for a paint it's a different matter, and I'll be using linseed paint when the exterior comes up for redecoration.

I presume you're after some sort of clear finish, or at least one that lets the "woodiness" of the building show through. This is tricky, beacause clear finishes are not good at stopping uV light, which contributes greatly to the break down of surface fibres and colouration. Hence the reason that most conventional woodstain products are quite heavily pigmented.

You might like to have a look at the Osmo range of exterior finishes. These include a water-based wood preserver, plus a wide variety of transparent, tinted and opaque finishes. I've not yet put these to the test, but my experience with other Osmo products gives me confidence in them as a manufacturer of top-notch finishes.

Raw softwoods will last for a while without any treatment, depending on the species. But ultimately it's all vegetable matter and given the right conditions it's going to turn into compost. Applying something out of a tin can help in two ways: by providing a water-resistant coating so that water runs off and the wood stays drier, or by leaving traces of biocide on the wood which inhibit the bacterial / fungal growth which leads to breakdown of the timber. Or both. Of course, many decay problems are a result of poor design detailing leading to water retention.

Perhaps you should leave on half of the building untreated, put something on the other, then tell us in 10 years time how it's getting on.

 

[skier-hughes]

Perhaps you should leave on half of the building untreated, put something on the other, then tell us in 10 years time how it's getting on.

Not sure I like that idea too much after spending 6k on it

It's scandanavian wood and supposed to be good quality. I'll look at Osmo products.

Clear was picked for the woodyness and to keep it lighter, which would look better in it's location. Also my experience of painting decking previously with cuprinol decking paint left a very patchy looking surface, not what I want on 5mx4m walls!!!!


Ta everyone.

Graham

 

[biffvernon]

My experience from experiments is that linseed oil on it's own on exterior woodwork is a disaster. Expect it to go black and mouldy within a year,

The tendency to promote mould growth happens with linseed oil that has too much protein. I'm no expert so stand to be corrected on this, but I gather the first cold pressings are pretty pure oil and the later squeezings, sometimes at higher temperatures, allow other stuff that forms nutrients for moulds to be included. This can be removed. To refine linseed oil mix half and half with water in a jar, shake vigorously and leave to stand. Pour off the water. The stuff you don't want dissolves in the water leaving the oil cleaner. Repeat this half a dozen times over a few days and you will have very pure oil that is a much paler colour than when you started.

Or you could just buy the stuff from Holkhams.

I was talking to someone recently who coated his exterior joinery with old engine oil. He'd been doing this for many years. The wood certainly hadn't rotted!

 

[Nemesis]

I slapped a coat on me larch birdboxes last year - actually year before (doesn't time fly when you are permanently inebriated?) and they are as good as new.

Not sure how scientific the experiment was though.

Maybe a nice coat of dark green linseed oil paint would look good.

 

[skier-hughes]

Or you could just buy the stuff from Holkhams.

I was talking to someone recently who coated his exterior joinery with old engine oil. He'd been doing this for many years. The wood certainly hadn't rotted!

The farmer always coated exterior woodwork with the old engine oil, I'd rather have something a little less smelly and brighter looking.

So Biff, would you use Holkhams linseed, nothing or something else for an exterior wooden building?

Graham

 

[michael]

Obviously, Oil is water repellent and so undoubtedly using some kind of oil will be a suitable choice as long as its regularly maintained.
Not sure which is the best oil to use out doors but I’m sure that there are some purpose made oil based water repellent products on the market which have a small quantity of fungicide in them.
I’m no expert on this but I would have thought that if the wood is not allowed to dry out and is recoated with an oil based product on a regular basis at least once a year, then the water wont be able to penetrate the wood and natures rotting mechanisms which need water to survive will leave the wood alone, but as I said above it should perhaps have a splodge of anti fungal chemical in it just to prevent it becoming food for the funguses.

Alternatively, a drier, colourless, and lower maintenace option for protecting wood is I understand “Borate treatment” now available in pastes and powders rather than the old boron rods.
Have a look at this American website :-

http://www.logcareproducts.com/caretips/lhcmaint/standtime.html

I think they know a thing or two about the protection of log cabins.

 

[biffvernon]

Coating your log cabin with expensive linseed oil would make you substantially poorer but not increase the lifespan of the building.

Boron-based treatments don't do so well in the rain so might have a similar effect on your purse and building.

The 'have a splodge of anti fungal chemical' approach to timber treatment is best avoided too.

Graham, you haven't said what sort of timber it it. Larch, Douglas fir, Scott's Pine or some whitewood such as sitka spruce?

Have you considered Falun Red?

 

[skier-hughes]

It's a redwood, but I'd rather go for something clear if I could, ok the oil would cost about £150, but if it does a good job and gives me the finish I want I'd rather pay that than £100 for something just as good but not looking how I want it, if you see what I mean!!

 

[biffvernon]

Yes, but you seem a little confused as to what it is you want.

 

[skier-hughes]

I have a new baltic redwood timber log cabin.
I want to put something on the wood to prolong it's life.
I would prefer something that shows off the natural wood look.
Cost as such isn't an issue.

What would you recommend?



Graham

 

[biffvernon]

Not linseed oil.

Creosote would preserve the wood but not the look so you'll be going for one of the clear fungicidal treatments that firms like Cuprinol produce.

Or just leave it be - it will probably last quite a long time.

Or keep it indoors.

 

[skier-hughes]

Ok ta

I'll bring it in, Jo'll be delighted

 

[Ian Bond]

Graham

Is any of the stuff here any use to you?

http://www.traditionalpaint.co.uk/oscolor.html

You seem determined to keep the natural wood colour, rather than paint, otherwise I'd suggest looking at County Colour. You may prefer the Holkham paint though if you already use that.

There's a clear wood impregnation treatment at the bottom of the page, in addition to the various paints and waxes.

Osmo Wood Impregnation WR is a clear wood
impregnation for exterior use. Preventive against animal and
vegetable pests such as blue stain, rot and insect decay.
Penetrates easily and deeply into the wood, is water repellent,
and reduces swelling and shrinking. It has a very low odour
during application, and is completely odourless when
dry.

May be worth calling them for advice - I'm also assuming that you don't want the wood to end up with a glossy, varnished, 1970's pine clad kitchen look!!!??

 

[skier-hughes]

Thanks, good link.

 

[Toby Newell]

Leyland clear woodstain (why they call it that is beyond me) MICROPOROUS i.e. allows wood to breathe so moisture can escape naturally rather than blistering or peeling, think of it as Goretex for wood. Apply 5 coats. Will last 5 years, although you will probably still be coating in five years... Osmo and similar is microporous and similar in that it is a thinned out varnish in reality will look better but virtually no protection.

Osmo, I could go on...

Linseed oil, omg I don't want to go there (just smile sweetly) I could go on...

I don't have much experience of wood preservatives but would presume a clear spray coating of one before the finish goes on would be a highly sensible idea (allow couple of weeks to dry before applying coating and coat pref in warm, at least not wet weather! if poss) I'm sure you could thin Microporous varnish and spray it with an airless paint sprayer.

And... actually uv light doesnt really knacker wood, trees seem to quite like it. I think it's the combination of moisture ingress/egress AND thermal expansion/contraction that makes a fixed surface like an applied finish crack up when mated to an expanding and contracting/swelling substrate like wood, pigments just hide the colour fading that occurs no matter what bs the manufac says, I think you will find 99% of clear commercial finishes have inbuilt uv inhibitors, if they didn't all lacquers and clear coatings would peel within months in sunlight. Peter Bowyer (a 63 year old French Polisher) introduced me Microporous and I have actually seen doors he has coated 5 years ago and they are fine.

btw. I studied materials engineering at Uni, am a French polisher and an annoying know it all. I do know my wood though.

Toby