TUNG OIL – prolonging its shelf life (An old dog learns new trick)
Most traditional woodworkers tend to favor traditional finishing techniques. We talk about chemical staining, French Polishing, milk paint, and making our own varnishes. Hardly an area of interest for the newly initiated. But one finishing technique that is appreciated by both indefatigable traditionalists and complete novices is the use drying oils. They’re nearly foolproof to apply and, with a little patience and elbow grease, provide one of the finest finishes available. The term “hand-rubbed” oil has a certain amount of panache about it and with good reason, it’s an absolutely beautiful finish. BLO (boiled linseed oil) or Tung oil, you choose.
Of course anyone who has used an oil finish has probably experienced what happens to a partially full can or jar when it is left on the shelf for as short a time as several weeks. It begins to gel then harden. Many people think that they have purchased “old” product from their supplier. But the truth of the matter is that the oil is doing exactly what it supposed to do, it is drying and hardening in the presence of oxygen. All you have to do is replace one expensive can of oil that “hardened up” prematurely to realize that you’ve got to take steps to optimize its shelf life. That means that you have to minimize or completely eliminate the oxygen left in the can prior to storing any remaining oil. There are several ways to do this. One old method is to fill your can with marbles or aquarium pebbles. The addition of these solids raises the liquids level and minimizes the amount of oxygen left in the can. A more current method is to use an inert shielding gas (like argon) to displace the oxygen left in the partially full can. This method works well. Simply hold the lid close at hand, shoot a little gas into the can, then “put the lid on it”. As I said, the method works well, but many folks can be a little “put off” when they pick up that can of shielding gas. It really doesn’t feel like there’s anything in there.
But while continuing to look for methods to improve my own finishing techniques (really all woodworkers want to build unfinished furniture), I stumbled across a tip for improving drying oil shelf life. It is from the site of a very well respected tung oil producer. It’s simple – so simple. It works. I’ve tried it.
Float the oil on water. That’s right! Take that can, or preferably a jar, over to the sink and run water into it. Bring the liquid level right up to the top and stick a lid on it. The OIL FLOATS!
You will have to change one part of your process though. You’ll have to use a basting syringe, or some like device to withdraw the oil from the container and place it in a smaller container that will accommodate your method of application (brush, rag, abrasive pad, etc.). However, this is a good thing as leaving the container open while applying the oil expedites the gelling since the surface of the oil is exposed to oxygen.
So try it. It’s cheaper than marbles or gas. And, believe me, it’s a lot easier to “suck up” a little oil as you need it than it is to pour that expensive oil from a gallon jug that’s full of aquarium pebbles.