Tung Oil Question

[EricRN]

Hi all,

Quick question--Does Tung Oil (100% pure, not the stuff labeled tung oil but consisting of a bunch of other things) go rancid and, if so, what's the approximate shelf life? I'm in Maryland, to the extent climate matters. Also, would something like bloxygen help keep it fresh?

It's the time of year to refinish my patio furniture. I've been wanting to move to a pure tung oil finish for my bowls, cutting boards, and spoons so I'm inclined to just buy a big gallon jug of tung oil for the furniture and the cuttting boards. But I probably won't use it all and don't want to drop that much coin if there's a decent chance it will go bad.

Thanks,
Eric

 

[jttheclockman]

Eric I will give you my thoughts and do with them as you wish. First pure tung oil is tough to work with in that it takes forever to dry. That is why they use driers mixed in with it these days. It is in the line of pure linseed oils. With that said if it is pure than shelf life should be a very very long time as long as stored in cool dry place. yes bloxygen can help but I do not see a need. Keep lid tight. Ideal thing is to downsize the container if possible to limit air space when used. Transfer to smaller can if possible.

 

[monophoto]

I'm pretty much in agreement with John. Tung Oil may be the perfect finish in most respects - it penetrates into the wood, especially when thinned with a solvent, cures to form a protective finish in the wood (not on the surface), and is both water resistant and food safe. On the other hand, it does take a while to cure, especially if it is not thinned, so its not a super quick finish to use.

I use it in two ways. For a food safe finish, I mix equal quantities of pure Tung Oil (I prefer Hope's - when I can find it) and a food-safe limonene solvent. The combination smells wonderful, penetrates very well, and dries to the touch in a few hours. I usually apply three coats, buffing with a gray Scotchbrite pad between coats. I don't consider it thoroughly cured until I can no longer smell the orange oil.

My standard finish for items that don't contact food is to mix pure Tung Oil with equal quantities of a high quality alkyd varnish (McCloskey's - when I can find it) and a solvent. I've usually used turpentine as the solvent, but I think I'm going to try the limonene solvent the next time I mix a batch. This mixture looks and acts very similar to Waterlox but is less expensive. I apply and let it soak in, and then after 15-45 minutes I wipe off any excess. I generally apply three coats, letting it cure 2-6 hours between coats - and overnight is even better. I also buff lightly between coats using a Scotchbrite pad. After the third coat, I let it cure for at least 24 hours and then buff using the usual three-wheel process.

Tung Oil doesn't go rancid like olive oil, but it will cure if exposed to air. My experience is that if I reseal the container carefully (I will often cover the threaded opening with a thin piece of polyethylene (like from a zip-lock bag) before screwing on the cap so that the plastic acts as a gasket to prevent air from getting into the jug), the oil will remain good until I use it up. So far my experience is that Tung Oil thinned in a solvent seems to last quite a long time, but the Tung Oil/Varnish blend does start to cure in the jar after a few months. But to be safe, I only mix a small amount - 2-3 ounces - and store it in glass jars with tight lids (recycled spice jars from the supermarket).

 

[EricRN]

This is all really helpful. Thanks, guys. Dry time doesn't bother me that much. I wish I had enough time to woodwork that dry time would slow me down. But, with a "real" job and three kids, that just isn't the case.

 

[KenB259]

I started buying these a few years ago. I love them.

 

[monophoto]

Ken

"Stop-Loss" bags are great, but I had a very bad experience with one.

I had opened a new quart can of McCloskey's Man-o-War alkyd varnish to make up a new batch of my Tung Oil varnish blend. I use a measuring scoop made from an old 35mm film canister to transfer small amounts of varnish, oil and solvent to my glass storage jar, and then turned by attention to storing the remaining varnish. I poured varnish from the can into the 'Stop Loss bag" using a funnel. The varnish is fairly viscous, so I had to pause periodically to let the funnel empty into the bag, and then resume pouring varnish. For safety, I did this over the garbage can that I keep in the shop.

My hands are relatively small (no crude jokes, please), so holding the can while pouring was difficult, and sure enough, the can slipped out of my hand and fell into the garbage can. Easily a third of a quart of varnish immediately mixed with the shavings, sawdust, and other trash in the garbage can. Bad words were said! Some of it also splashed on me, but fortunately I was wearing an old flannel shirt that I keep as a 'house jacket' for cool weather, so now my house jacket has a large area of micarta on the front. I don't know if it would wash out - my wife bought the shirt at a next-to-new shop thinking she would use it for a craft project, but later changed her mind and I adopted for wearing around the house; we've never washed it and probably never will.

So when I think of 'Stop Loss bags', I'm torn between that other use, and my bad experience with a can of expensive varnish.

 

[KenB259]

Ken

"Stop-Loss" bags are great, but I had a very bad experience with one.

I had opened a new quart can of McCloskey's Man-o-War alkyd varnish to make up a new batch of my Tung Oil varnish blend. I use a measuring scoop made from an old 35mm film canister to transfer small amounts of varnish, oil and solvent to my glass storage jar, and then turned by attention to storing the remaining varnish. I poured varnish from the can into the 'Stop Loss bag" using a funnel. The varnish is fairly viscous, so I had to pause periodically to let the funnel empty into the bag, and then resume pouring varnish. For safety, I did this over the garbage can that I keep in the shop.

My hands are relatively small (no crude jokes, please), so holding the can while pouring was difficult, and sure enough, the can slipped out of my hand and fell into the garbage can. Easily a third of a quart of varnish immediately mixed with the shavings, sawdust, and other trash in the garbage can. Bad words were said! Some of it also splashed on me, but fortunately I was wearing an old flannel shirt that I keep as a 'house jacket' for cool weather, so now my house jacket has a large area of micarta on the front. I don't know if it would wash out - my wife bought the shirt at a next-to-new shop thinking she would use it for a craft project, but later changed her mind and I adopted for wearing around the house; we've never washed it and probably never will.

So when I think of 'Stop Loss bags', I'm torn between that other use, and my bad experience with a can of expensive varnish.

That would certainly suck. I have had no bad experience with them.

 

[dogcatcher]

Ken

"Stop-Loss" bags are great, but I had a very bad experience with one.

I had opened a new quart can of McCloskey's Man-o-War alkyd varnish to make up a new batch of my Tung Oil varnish blend. I use a measuring scoop made from an old 35mm film canister to transfer small amounts of varnish, oil and solvent to my glass storage jar, and then turned by attention to storing the remaining varnish. I poured varnish from the can into the 'Stop Loss bag" using a funnel. The varnish is fairly viscous, so I had to pause periodically to let the funnel empty into the bag, and then resume pouring varnish. For safety, I did this over the garbage can that I keep in the shop.

My hands are relatively small (no crude jokes, please), so holding the can while pouring was difficult, and sure enough, the can slipped out of my hand and fell into the garbage can. Easily a third of a quart of varnish immediately mixed with the shavings, sawdust, and other trash in the garbage can. Bad words were said! Some of it also splashed on me, but fortunately I was wearing an old flannel shirt that I keep as a 'house jacket' for cool weather, so now my house jacket has a large area of micarta on the front. I don't know if it would wash out - my wife bought the shirt at a next-to-new shop thinking she would use it for a craft project, but later changed her mind and I adopted for wearing around the house; we've never washed it and probably never will.

So when I think of 'Stop Loss bags', I'm torn between that other use, and my bad experience with a can of expensive varnish.

I use 60ml syringes to measure my custom mix finishes. I only mix small amounts at a time, about a baby food jars worth. I use the syringes several times. I "rinse" them in mineral spirits. After the mineral spirits rinse gets funky I pour it on my trailer floors as a sealer.

The graduations are marked and easy to see. For gunstocks finishes I use 4 special mixes. Easy and fast. About 25% of the cost of Tru Oil.

 

[leehljp]

My first experience with pure tung oil was when I was living in Japan. I knew I had tung oil as it said so on the label in English. Beyond that, all the instructions were in Japanese and at the time I was not yet fluent enough in reading Japanese.

One morning I applied it to a piece of walnut (a walnut platter) and let it set. That afternoon it was still as wet as it was that morning. I let it set for 3 days and still wet. I wiped it off as much as possible and applied another coat. 3 days later it was still wet. I was aggravated but let it set for a little over a week. When I checked it that time, I had the nicest finish I ever had on a project like that.

All of this was before the internet. Later, in subscribing to Fine Woodworking, I learned that I had done almost exactly as I should have in finishing with pure tung oil.

It takes time, but it sure is worth it too. But Dryers do help and they don't take away from the finish it produces either.

 

[calabrese55]

Here is some pretty straight forward info on tung oil from a guy called Stumpy Nubs
basically tung oil , according to him, is not always tung oil .

calabrese55