# Boiled Linseed Oil and oak



## AndyT

I just bought some boiled linseed oil.
It says on the bottle it's suitable for everything except oak.

What happens if I use it on oak?

(I'm sure plenty of people have done so!)

Andy


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## DaveL

I would like to know as well, I have use BLO on oak, with no obvious bad side effects. :-s


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## Woodfinish Man

In our opinion there's no reason why it shouldn't be used on oak. We've been recommending it for +60 years with no problems.

Ian


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## AndyT

I asked the same question a while back: https://www.ukworkshop.co.uk/forums/boiled-linseed-oil-and-oak-t33865.html?hilit= linseed

I used it, on oak; it's fine.


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## Jacob

"Boiled" has hardeners and can set like a varnish if it's applied thickly, whereas raw will take a lot longer to dry (to oxidise, not really drying), giving it longer to soak in, for a finer oil finish.


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## SP

I only ever use BLO on oak.


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## jeffinfrance

thanks jacob, but i can't see any additional ingredients listed. does the boiling create the hardners from existing mollecular compunds in the oil?

jeff


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## sneebz

boiled linseed oil is not boiled ,it is heated and then metal compounds are added so that it dries faster
no reason to not use on oak.


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## zb1

The only thing I could think is that if the BLO contains metal compounds that the brand you have bought might contain ferrous metals therefore creating the possibility of turning the oak blue/purple. It's a theory.


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## Sgian Dubh

It's surprising to see this old thread resurfacing ... yet again. I too have seen the warning to not use boiled linseed oil on oak, one which I've happily ignored all of my furniture making life. I don't recall seeing these warning back in the 1970s, '80s and '90s, and they seem to have started appearing sometime in the 00s-- of course my memory could be playing tricks.

However, and without any real sources to back it up, I think the warning may have something to do with any protein or food like qualities in the oil when used on exterior furniture in particular. For instance, when I make outdoor furniture from oak (or other woods naturally suitable for this purpose) there's a decision to be made about applying a finish, or not. Oak is a durable wood anyway, so I never consider applying any sort of film forming finish such as paint or varnish, as these require maintenance which, frankly 99% of customers won't do, or only do poorly, so applying paint or varnish is really a waste of time. Generally it's just a question of leaving the wood bare and letting it age and weather naturally or for a more attractive picture for the portfolio, slapping a bit of linseed oil on to bring out the colour.

What I have noticed is that oak left bare and stuck out in the weather goes through stages and takes on the naturally weathered look after a year or two. Stuff that's got linseed oil on it looks attractive for a couple or three months, and then goes through a phase where there are spots of particularly unattractive black mould (or perhaps bacteria) nourished, I suspect by some protein or some other foodstuff in the linseed oil. After a while the natural ageing takes over as whatever foodstuff is in the linseed oil is all used up, and those especially nasty looking fungi (bacteria?) seem to disappear. I suspect that if there's a lot of linseed oil applied, or it's applied two or three times a year, that ugly black stuff will keep thriving until that particularlar food source is all gone.

Of course, I could be talking cobblers, but that's my theory, so I'll stick to it until someone offers better evidence to the contrary, ha, ha. Slainte.


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## Peter Sefton

I have just asked Bob the polisher who is here running a finishing course for us today, He has not seen any problems with linseed oil on Oak but says he wouldn’t use it on much more than cricket bats so not a real fan of its use.
The only thing I have heard is that it will/can turn Oak black, but have not seen this myself.


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## Gary Morris

I asked the question on another forum (US) they all said the same as above - no problems or never heard of the warning, bar one, who said like Peter said, it may discolour the oak.

Gary


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## Peter Sefton

I was told of this by a lecturer who used to teach history for me and he had seen or been aware of the problem on some restoration work at 

http://www.rodmarton-manor.co.uk/

Well worth a visit if you like your Arts and Crafts


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## Jacob

Peter Sefton said:


> I have just asked Bob the polisher who is here running a finishing course for us today, He has not seen any problems with linseed oil on Oak but says he wouldn’t use it on much more than cricket bats so not a real fan of its use.
> The only thing I have heard is that it will/can turn Oak black, but have not seen this myself.


Look at a half timbered building. The black is due to oil (usually linseed) unless they have also been painted.
Old oak beams freshly exposed go a chocolate brown with new linseed (or any oil AFAIK) and this will darken slowly to black.
First time I saw this I though it was stain, but I've seen it and done it many times since.


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## zb1

Half timbered "Black and Whites" are a Victorian decorating fad. Nothing to do with oil blackening the timber. Externally exposed oak will eventually throw off any oil or stain and revert to type. Type being silver grey.


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## Jacob

zb1 said:


> .....Externally exposed oak will eventually throw off any oil or stain and revert to type. Type being silver grey.


Unless someone comes along and puts some oil back on.


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## pidgeonpost

I've just put together an Oak plank top for an otherwise sound outdoor table, and picked up on this thread after being surprised at the warning on the bottle of BLO. I'm going to use it anyway, but my query relates more to the preservative I was going to use before applying the BLO - Barrettine Universal Preserver. My hope is/was that this is pretty deep-penetrating stuff that will not prevent the BLO from penetrating the timber. Any thoughts or experience of this please?
My other concern is the toxicity of this preservative. It's pretty nasty stuff. Maybe I should just use BLO...


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