Tung Oil question

And how, exactly, did the sales person know that? The average can of finish has little useful information about the formulation or anything else. You might try getting the msd sheet for the finish which may give you some ideas about what is or is not in the can.

One possibility would be to put the finish in a squeeze bottle so that you can expel most of the air or use one of those spray cans of an inert gas.

Buying small cans just might save money in the long run.

Bill

Keith Young wrote:

If it contains no dryers, it should have a longer bottle life after air is admitted than tung with dryers. The answer is to use it and see what happens. Friction warm some into something you're turning until refusal, then wipe dry after a half hour should any still be on the surface. Keep it room temp or better for a week, should be cured enough that it doesn't show fingerprints from warming by hand.

You can also rub a barely cohesive film on a piece of glass, warm it with a bulb for a day or three and check it out. Should skin to a leathery film.

In short, there are two options. It's good, or it isn't. Decant and protect what you've left in the bottle from excessive oxygen as advised. I throw in marbles.

Hi Keith

Tung oil will cure in air, it is slow curing, there is pure tung oil that is "heat treated" to speed up the curing, also some times thinners and dryers are added to have the oil penetrate more and cure quicker.

The problem as I see it is the oil gets aired every time we open up the can it is in, and is curing while it sits in that can, and is cured if we take to long before using it all.

Also it's curing, not drying, so adding a thinner to it will not undo the curing, if it gets to jell, dump it.

The only way I know of how to make the oil useable longer, is, as soon as you get your new can of tung oil, divide it into small containers, filled to the brim, and tightly closed, then store in a cool place.

Then use a small can, (I use one of those 2 ounce CA glue bottles) also keeping the can in use closed, does help some, even so the air already in the can will be curing the oil, don't shake the can, like mixing, there is nothing to mix except oil and air, not a good idea, and keep it cool if possible.

Here's a link to some more info from Lee Valley

Have fun and take care Leo Van Der Loo

Keith Young wrote:

I displace the air with propane from my torch, then seal the can. Works a treat.

djb

Well, this is disappointing as I bought my first can of tung oil a few weeks ago. I wondered why it had a small metal cap creating an air tight seal underneath the plastic cap. David Marks on DIY's Wood Works always praises Tung Oil for the finish it puts on wood, but I've never heard him mention this gelling problem.

Would turning the can upside down after use help at all ? It seems like this would cause the oil in the bottom of the can to gel up first. When you turn the can back over to use it, hopefully the gel would remain at the bottom. Any thoughts on this ?

I guess I'll get some small jars and fill those up to save as much as I can.

Hi Brad

As you turn your can upside down the air in the can will travel through the oil, and exposing more oil to the air, just get the small jars and store cool that will slow down the curing and there will be no additional air exposure.

Have fun and take care Leo Van Der Loo

Brad Curfman wrote:

I have had the same problem. When I buy a quart can it always seems to turn to gel before I barely use it. I did buy some Behr Tung Oil Finish at Home Depot last time and it has not gelled after 6 or 8 months. I'm sure it is far from pure. In fact the word "Finish" in the title is a give away, but it works well and gives a nice finish.

If you go to David Marks DIY site or listen to his spiel closely, you will see/hear that the finish he uses is an over the counter combination of tung oil, poly, and (I think) linseed oil. Not sure of the last ingredient. But it's not pure tung oil.

Earl

David Marks seems to use General Finishes' Seal-A-Cell.

You can tell by the can if you look closely when he is using a "tung oil finish" straight from the can. He often uses a cup or jar for his finishes and describes it as a mixture of "tung oil, linseed oil and urethane." Just my observation, Roy Fek