Decided to try PTO

[Bill Jobe]

I decided to try a can of Lee Valley Polymerized Tung Oil. Had a piece all prepped and ready for a first coat which I intended to cut considerably with mineral spirits.
Then I noticed they
recommend mineral oil. So I decided not to open the can just yet and find out what the difference is.
As best I have gathered most who use PTO cut it with mineral spirits.

Does it matter, other than the food-safe difference?

[Jim Becker]

Why do you want to cut the oil? AFAIK, you only need to do a series of light applications, rubbing it in and wiping off any excess.

[Steve Eure]

I have never used that particular product from Lee Valley, but have used other brands of tung oil. I am inclined to be on the same page with Jim Becker on this. Why would you want to cut it with MS or MO for that matter. I always apply a light first coat and let it sit a minute or two and then rub it in. Second and every other coat afterwards is wet sanded with 600 grit and tung oil and wiped off and let dry for approx. 24 hrs. Time may vary depending on temp, humidity, etc. This results in a spectacular smooth finish and is easy to maintain, at least in my experience.

[Bill Jobe]

I want to cut the first coat.
I'm going to use mineral spirits as I read since posting that mineral oil is a non-drying oil. Don't want that underneath several more coats.
Correct me if I'm wrong but I think mineral spirits totally evaporates?
I think the problem arose because in most of the text I've read on the subject the two products seem to be identified interchangeably.
In several cases I've read that cutting the first coat helps get the oil deeper into the wood than it would normally.
Lee Valley also sells a sealer made to use as a first coat and it looks to be nothing more than PTO cut to 20% with 80% thinners.

[Wayne Lomman]

Cutting it to that extent is going to leave you with nothing on the job. It's just putting solvent on to let it evaporate along with the contents of your wallet for no good reason. The uncut oil will penetrate just fine and you will get a result for your effort. Cheers

[Alan Rutherford]

Mineral spirits is paint thinner. Mineral oil is - oil. This pdf from Lee Valley suggests thinning the first coat with MS, not MO, to improve penetration. Makes sense to me.

[Edit: That pdf is about 100% tung oil. This one is about polmerized and doesn't mention thinning.]

[Stan Calow]

It won't penetrate any deeper with solvents, will it? The oil molecules stay the same size.

[Alan Rutherford]

Thinning the first coat works well with many finishes, whether because of molecule size, the viscosity of the solution, drying time, or whatever. I normally thin at least slightly the first coat of any product that lends itself to thinning.

The pdf I linked to is for 100% tung oil and probably isn't relevant. This one is about polymerized tung oil and doesn't mention thinning at all but it does say to clean up with mineral spirits. I'd still say that if he's going to thin, he should use mineral spirits. If the can says to thin with mineral oil - I'd like a second and maybe a third opinion, or I'd just not do it.

[Bill Jobe]

Yeah, mineral oil is definitely not what to use. It does not dry.
Here's one source I read:


http://www.woodworkdetails.com/knowl...shing/tung-oil

Polymerized is thicker, the heating process already having taken place, so since Lee Valley cuts it by roughly 50%, it seems to me appropriate to cut it at least another 50% for the first coat, then full strength from there on.
I have read from a number of sources that cutting it on the first coat gives a deeper view of the grain.
This piece is kinda special since it was harvested in my front yard, the root ball of a yew bush that was already growing when we bought this place in 1989.
And I almost lost it by not following proper drying procedures after roughing it and it became mold infested. I dried it quickly and had roughed it thick enough to salvage it. I don't want any more dumb mistakes.

[Bill Jobe]

It measures 8" tall, 6" at the rim and 5" at the base. Root ball of a yew bush.
I don't know how it rates esthetically. I just roughed it out using as much as I could and this is what I came up with. Some stock was lost due to the mold.
And the wife likes the shape, so it may actually earn a location other than the "scrap pile" where most of my pieces end up.

[Jim Becker]

That's a beautiful piece of wood and should really "pop" with the oil!

[Bill Jobe]

That's a beautiful piece of wood and should really "pop" with the oil!

I hope so,Jim. I hope PTO is a wise choice.

[Jim Becker]

I've for a long time use Tried and True which is a polymerized BLO product...so not hugely unlike what you're wanting to try on your piece. I suspect you'll enjoy the results.

[David Kreuzberg]

I think you misread the label...no mention of mineral oil.

Polymerized Tung Oil This is pure tung oil that has been given extra heat treatment to encourage polymerization and faster initial drying.Because the treatment increases the body of the oil, this product contains 50% mineral spirits to dilute it to a workable consistency. Polymerized tung oil provides a high-luster finish and is suitable for heavy-use items. It is an excellent choice when you want a simple finishing method that also gives you beauty and durability.

[Bill Jobe]

Thanks for catching that, David. I most likely pick that up while surfing for links. Most landed me on other forms. I think that's why I was making the point to begin with.....there is much confusion and there are strong differences of opinion on the suject.