# Thinning BLO - why?



## Longknife (Oct 25, 2010)

A common recommendation when using BLO is to thin it with white spirit or turpentine up to 50%. This is the way I've always done it, but lately I have been wondering about it. The reason should be that the thinner liquid will penetrate the wood more easily, but does it really?
The ability to penetrate depends on the size of the molecules of the oil and that doesn't change when thinning the oil, does it? So what I've come to think is that what happens is that the spirit will penetrate deeper than the oil but later evaporate so the result is no deeper penetration of the oil. Anybody have an opinion or knowledge on this matter?


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## Brink (Nov 22, 2010)

I've only heard about thinning raw linseed oil with turpentine. Supposed to help it dry faster


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## cabinetman (Jul 5, 2007)

I wouldn't use raw linseed oil, but rather boiled linseed oil. Thinning BLO carries the oil deeper, and allows better penetration of the wood than straight oil. I do finish applications with BLO full strength.












 







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## Longknife (Oct 25, 2010)

cabinetman said:


> I wouldn't use raw linseed oil, but rather boiled linseed oil. *Thinning BLO carries the oil deeper, and allows better penetration of the wood than straight oil.* I do finish applications with BLO full strength.
> .


Yea, as I said, that's the general conception, but do you *know* that for a fact? Any scientific proof?


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## cabinetman (Jul 5, 2007)

Longknife said:


> Yea, as I said, that's the general conception, but do you *know* that for a fact? Any scientific proof?


Do I *know* that for a fact...*yes* I *know* that for a fact by doing that application. It's as scientific as I can get.












 







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## Longknife (Oct 25, 2010)

cabinetman said:


> Do I *know* that for a fact...*yes* I *know* that for a fact by doing that application. It's as scientific as I can get.
> .


Sorry if I offended you by using some bold letters. I'll try to talk smaller.
What I mean is how do we know that the oil penetrates better when it's thinned?


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## cabinetman (Jul 5, 2007)

Longknife said:


> Sorry if I offended you by using some bold letters. I'll try to talk smaller.
> What I mean is how do we know that the oil penetrates better when it's thinned?



Well for one thing...I'm saying it does. You can try it for yourself. When I do use BLO, the first few applications I thin. When I apply it to the surface it just goes inside the wood and disappears like magic.:yes:












 







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## BWSmith (Aug 24, 2010)

Longknife....could you check penetration on vary'ing thickness's of veneer........eyeing the backside.

But in general gotta say,finish specs are SO largely dependant on techniques that any empirical data is going to have suspects.......So,the way C-man does it,works for him.I may be a newb and just can't get the technique quite right and it all ends up a mess.Just spitballin,BW


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