On the recommendation of a luthier, I got some polymerized tung oil from Lee Valley Hardware to use on my banjo. I thought tung oil was safe, maybe not salad oil safe, but safe. This stuff comes with warnings that it’s toxic, inflammable, and if I hadn’t put it down and backed away from Ground Zero, maybe radioactive and explosive.:eek: I get that the adjective “polymerized” modifies “tung oil,” but what’s the straight dope on this stuff?
Should I push my car down the block before creating an ignition spark and getting out of Dodge, or can I apply it with wild abandon? To my banjo. Which is not a slang term. Thanks.
Marking papers all day means I can’t proofread worth a damn. Sorry.
On the recommendation of a luthier, I got some polymerized tung oil from Lee Valley Hardware to use on my banjo. I thought tung oil was safe, maybe not salad oil safe, but safe. This stuff comes with warnings that it’s toxic, inflammable, and if I hadn’t put it down and backed away from Ground Zero, maybe radioactive and explosive. I get that the adjective “polymerized” modifies “tung oil,” but what’s the straight dope on this stuff? Should I push my car down the block before creating an ignition spark and getting out of Dodge, or can I apply it with wild abandon? To my banjo. Which is not a slang term. Thanks.
Its fine. Polymerisation is how it cures. You can get partially polymerised, and plain Tung Oil. The partially polymerised oil has been boiled, and that accelerates the reaction. It takes a lot less time to cure than the unboiled stuff - although the purists will argue that because it becomes more viscous, it doesn’t provide the absolute best surface finish. Unboiled takes weeks to cure.
It is a whole mess of hydrocarbons - it is after all a plant sap extract. It won’t hurt you much if you drink it - might make you feel sick. But like anything with non-polar liquids in it, if you drink it and then vomit you might inhale some liquid, and that suddenly becomes really bad. And it burns. Of course it burns, it is resin out of a plant. Also, some people might be allergic to something in it - just like some people are allergic to some plants.
As paints and finishes go, it is pretty tame. I assume you are intending treating the fingerboard.
ETA - Marking - man there is one thing that I don’t miss from my days as an academic.
You have a car but you are worried about tung oil because its toxic and inflammable? What do you think your car runs on? Sunshine and kittens?
If you’re talking about the sort of oil products marketed for finishing “salad bowls” and the like, note that Bob Flexner (frequently published expert on the subject of wood finishing) argues that ANY wood finish is safe enough to eat off of when cured:
http://www.woodcentral.com/articles/finishing/articles_497a.shtml
(Obviously many wood finishing products in their “out of the tin” liquid state would be quite “poisonous” if ingested or inhaled excessively, are (in)flammable, etc…is that really a surprise??)
Unless you’re planning to eat that banjo, it’s safe.
I know people who get sick when using tung oil. Headaches and nausea for days afterwards. They cannot be around it at all.
The substance has been found to cause cancer, and to cure cancer.
But only in the lab. Somewhat unlikely to be true either way.
Its very similar to a very common food fatty acid, your body can’t be allergic to it and your body will consume it as food.
The Tung tree is a member of the Euphorbiaceae (spurge family), which is quite the rogues gallery in terms of toxicity, so it shouldn’t be a surprise if the oil contains irritants and toxic chemicals (at least in comparison to, say, linseed oil - which is derived from an edible seed).
But yeah, unless you’re going to pour it on a salad, or eat the banjo, then it should be possible to safely use the stuff.
I recently had a small fire in a metal rag bin at the house. The fire was spontaneous combustion. Tung oil was the last rag that I had thrown in the bucket. Other rags also contained linseed oil, tru oil and mineral spirits so hard to say for sure which one caused the fire. I was a littel suspicious it might be reactive with other chemicals I use.
Drying oils are notorious for self combustion as they oxidise. My money would be on linseed as the culprit there.
Similar question showed up in a woodworking magazine a while back (it was on food-safe finishes for a cutting board), they had the same answer - any normal woodworking finish is safe once it cures. I think that they had a link to an FDA article about this.
Thanks for the helpful comments, everyone. I take your point about the car, but I don’t rub my hands all over the car for hours at a time. It’s not that great a car. Will use the oil on the neck and fingerboard. It was originally finished with tung oil, not a shellac or lacquer. And yes, marking papers is enough to make me think about buffing up the banjo with tung oil and busking again.
The special feature of tung oil is that, once cured, it is even tougher than everything else. That’s why you choose tung oil.
Also the best available oil for curing cast-iron cooking ware.