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Raw vs boiled linseed oil

D

Don McDermott

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Name
Don McDermott
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Hello everyone, Don here from Building Lady Garnet. The oak I have bought for the keel, hog, etc, is all green, so in order to minimise cracks as it dries, I thought I'd apply some linseed oil to the timber, to slow down the drying. But I'm unsure if it's best to use raw or boiled?

When I looked up boiled linseed oil, it says not to use it with oak. Further research seems to suggest that no one can figure out why this advice is given, unless it's because it can cause staining on the oak (which, I should point out, doesn't matter to me because it's going to get painted with bitumen in the end).

But I was wondering if anyone had further views on this, and whether it is better to use raw rather than boiled... or if anyone thinks I should use something else entirely!
 
Have you got a link for that advice, Don? Maybe there is a context to consider?

I don't know, I'm not an expert on finishes. But for oak my favourite is a coat of BLO for colour and tone, followed by a hardwax oil, such as Osmo. My furniture is, of course, not ocean-going, but I've never had any problems. Perhaps the issue is that the oak is not seasoned? We need more info.
S
 
I've put both on oak, and one of them doesn't set properly for weeks. I assume that's the raw, but I can't honestly remember. I think the advice about linseed oil and oak is more to do with the nasty stale-urine colour that it goes. It certainly isn't going to stain the oak, and if you can stack the pieces so that they don't stick together then I can't see why linseed couldn't be used......although I doubt it's going to make any great difference to the rate at which the wood dries, or how much it cracks.

Do you want to be working this wood when it's seasoned? I can see why your planking stock should be dry, but as this is a clinker-built boat you'll be planking as soon as you've done the centre-line timbers, which should be relatively soon. And the centre-line timbers won't be dry anyway, will they?
 
Mike G said:
I've put both on oak, and one of them doesn't set properly for weeks. I assume that's the raw, but I can't honestly remember.
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Yes, the raw doesn't dry, but the boiled (well, chemically altered, these days) dries in a sensible timeframe.
Mike G said:
I think the advice about linseed oil and oak is more to do with the nasty stale-urine colour that it goes.
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I think it is rather nice golden colour. Perhaps the raw stuff is different.
Mike G said:
I can't see why linseed couldn't be used......although I doubt it's going to make any great difference to the rate at which the wood dries, or how much it cracks.
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I agree. It's like offering someone a net curtain to keep away the frostbite. It's not going to do any harm, but I'm not convinced it will do a lot of good either.

S
 
I've used boiled linseed oil in the past to soak green oak bearings for land rollers, it does make green oak go black in time when wrapped up in a bag, which I think is down to the drying additives added to the oil.

Raw linseed oil pretty much doesn't dry at all.
 
Mike G said:
I've put both on oak, and one of them doesn't set properly for weeks. I assume that's the raw, but I can't honestly remember. I think the advice about linseed oil and oak is more to do with the nasty stale-urine colour that it goes. It certainly isn't going to stain the oak, and if you can stack the pieces so that they don't stick together then I can't see why linseed couldn't be used......although I doubt it's going to make any great difference to the rate at which the wood dries, or how much it cracks.

Do you want to be working this wood when it's seasoned? I can see why your planking stock should be dry, but as this is a clinker-built boat you'll be planking as soon as you've done the centre-line timbers, which should be relatively soon. And the centre-line timbers won't be dry anyway, will they?
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Raw will set more slowly, yes, so perhaps boiled would be better. The centre-line timbers will still be very green when I assemble them, but the project will take years so they will be drying all the time, and I'd hate for any cracks to develop in the keel after I've already done a lot of planking.
 
Steve Maskery said:
Have you got a link for that advice, Don? Maybe there is a context to consider?

I don't know, I'm not an expert on finishes. But for oak my favourite is a coat of BLO for colour and tone, followed by a hardwax oil, such as Osmo. My furniture is, of course, not ocean-going, but I've never had any problems. Perhaps the issue is that the oak is not seasoned? We need more info.
S
Click to expand...

Boiled Linseed Oil

Use for finishing most bare exterior and interior timber, producing a slightly glossy finish with redish tint.
www.decoratingdirect.co.uk www.decoratingdirect.co.uk
 
Incidentally, here in France you can buy Linseed oil in any ordinary supermarket, 1L or 5L. It's readily available (along with acetone and hydrochloric acid). I assume it is BLO, I'll check next time I go. I'll try and find out how people use it out here.
S
 
Steve Maskery said:
Well I'm not going to stop using BLO on oak. I've been doing it for a long time and I am very happy with the results.
S
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This seems to be the consensus online, everyone who has used BLO on oak is perfectly satisfied with it!
 
Some woods go a really lurid yellow with linseed.

I would not expect it to stop splitting. Green woodworkers have tried all sorts of things, including boiling bowls in oil, can't say I've seen many success stories. How you cut the board out of the tree is the key bit.
 
I made a breakfront bookcase once out of ash. The piece itself was nice enough, but when I finished it, it did go that unpleasant urine colour. I can't remember what I used to finish it. Although if anyone has a Good Woodworking library, it will be in there somewhere.
S
 
Cabinetman said:
I haven’t the foggiest but I shall ask anyway, Don you say you’re going to paint Bitumen onto the oiled Oak, will the Bitumen be ok on top of the oil?
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Shouldn't be a problem, you can use oil-based or acrylic paints over linseed oil, once it has dried.
 
Cabinetman said:
I haven’t the foggiest but I shall ask anyway, Don you say you’re going to paint Bitumen onto the oiled Oak, will the Bitumen be ok on top of the oil?
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I presume he will machine the oak before construction, this is just to stabilise the oak and prevent it twisting.
 
I'll always prefer pure tung oil, it doesn't seem to darken the wood over time as much, first few coats thinned out ideally.
 
Mike G said:
There isn't a hope in hell that linseed oil would ever do that, I'm afraid.
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Surely it will slow the drying process though, which often reduces checking? Obviously it isn't going to eliminate checking/twisting completely but I figured it would help. I have certainly heard people claim that it works. Leo (from Tally Ho) used raw linseed oil on the purpleheart keel, and said that he was applying it to reduce checking.
 
For anyone wanting more on the BLO on oak question, I raised it years ago on another forum

www.ukworkshop.co.uk

Boiled Linseed Oil and oak

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
www.ukworkshop.co.uk www.ukworkshop.co.uk

The discussion there was a bit inconclusive, with some saying there was no problem and others reporting black staining.

(The odd cross-reference to my having asked the question earlier goes nowhere; I think the two threads got merged.)
 
Is it worth considering a thinned coat of the final paint. After all, all you are looking for is to partially seal the surface to slow moisture loss.

50% / 50% bitumen / white spirit perhaps?
 
Steve Maskery said:
FWIW, I've remembered the stuff that makes ash look like pee, it was Danish Oil.
S
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I imagine (but am guessing) that depends on the Danish Oil. As I understand it, Danish Oil is just a generic name for a mix of stuff. I bought a couple of different brands of it and they were completely different (both in the resulting wood colour and in the viscosity of the oil).
 
Maybe there is nothing to lose by putting some on, mind, if the Linseed oil doesent dry properly the worst case is you would be working with tacky/sticky wood.

My advice if your looking at long term storage, is to properly sticker the boards up, with some weight on the top, under a cover but allowing for ventilation, and in a place where the sun doesn't shine.

Although, IIRC, Leo oiled his Greenheart keel after it was made.
 
AndyT said:
For anyone wanting more on the BLO on oak question, I raised it years ago on another forum

www.ukworkshop.co.uk

Boiled Linseed Oil and oak

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
www.ukworkshop.co.uk www.ukworkshop.co.uk

The discussion there was a bit inconclusive, with some saying there was no problem and others reporting black staining.

(The odd cross-reference to my having asked the question earlier goes nowhere; I think the two threads got merged.)
Click to expand...
Years ago I had a brief correspondence with someone from one of the large finishes companies (I forget which) and I was told their Danish Oil was suitable for soft and hardwoods ............ except for oak. I tried to find out why but didn't get an answer.
 
Phil Pascoe said:
Years ago I had a brief correspondence with someone from one of the large finishes companies (I forget which) and I was told their Danish Oil was suitable for soft and hardwoods ............ except for oak. I tried to find out why but didn't get an answer.
Click to expand...
Again, I would guess it's the staining, oak is particularly bad for staining, even using spacer sticks for drying that are not oak can apparently cause staining. Again, for me, it doesn't matter, since all the planks are getting painted black anyway.
 
I’ve used boiled and raw linseed oil on both red and white oak. For both you need to put on thin and wipe off any excess in an hour or so. On red oak, the excess will leak from the pores for a while. BLO you can recoat in a day or two. Raw, I’d wipe again after a day and wait more like a week to recoat.
 
Steve Maskery said:
Incidentally, here in France you can buy Linseed oil in any ordinary supermarket, 1L or 5L.
Click to expand...
That's interesting. Is there some other use for it that I am not aware of? Why do French shoppers pick up a container of linseed oil along with their weekly shop? Do people cook with it?
 
I am not at all sure that the huile de lin we see in the supermarket is the same as the linseed oil used for protecting wood.

Huile de lin can be used to make vinaigrette and for cooking.
 
Raw definitely takes ages to dry, if ever.
Found I had to remove with some spirits and then apply BLO.
Used BLO on all the tables that were refurbished, thinned 30/70 then 50/50 then 100/100.
 
AndyP said:
I am not at all sure that the huile de lin we see in the supermarket is the same as the linseed oil used for protecting wood.

Huile de lin can be used to make vinaigrette and for cooking.
Click to expand...
Hmm, interesting. I didn't know that. But it's usually with the hydrochloric acid, turps and caustic soda, rather than with the vinegar and olive oil. And a 5L can wiould make an awful lot of salad dressing...

S
 
I think food grade linseed oil is usually sold as flax seed oil, some of the green wood workers prefer it for wood in food contact.

Raw linseed comes in gallons from equine suppliers; don't know why, I didn't know you had to do oil changes on your horse. But it is a cheap enough source if you need a big bottle !.
 
I believe what you want to do is coat just the end grain, not the whole timber. That is because wood dries more quickly from the end grain than face grain and that imbalance is what causes cracking. Over here the most commonly used product for this is called AnchorSeal, which is a wax emulsion. But a mix of boiled linseed oil and bees wax or paraffin wax will also do the trick. If you are treating just end grain, any staining will usually be cut off during final dimensioning.
 
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